The Blues lost 2-0 at Old Trafford and are now just four points ahead of Tottenham at the top of the table, having led by 10 points in March.
"We didn't play a good game and United deserved to win the game," said Conte.
"They showed more desire, more ambition, more motivation. In this case the fault is of the coach."
The Italian added he had not been able to "transfer the right concentration, desire, ambition to win this game".
Spurs have put themselves into title contention with a run of seven successive league wins, while Chelsea have had two losses in their past four games.
The teams meet at Wembley on Saturday (17:15 BST) in the first of the weekend's FA Cup semi-finals.
"I have concern because we have to work together and find quickly the right ambition to win this title," said Conte.
"If someone thinks it's normal for Chelsea to win the title, we started as underdogs after 10th place last season.
"Tottenham is in good form and playing with enthusiasm. We must find the same."
Courtois injured playing basketball?
Chelsea's preparation to face Jose Mourinho's side was disrupted when goalkeeper Thibaut Courtois injured his ankle during the week.
The Blues also lost full-back Marcos Alonso just minutes before kick-off because of illness.
Conte was asked about reports Belgium international Courtois was injured while playing basketball at a promotional event.
"After a defeat it is not right to go into this situation," said the Italian.
"Courtois had an injury during the middle of the week and for this reason he wasn't available but I think it is right to focus on the game and not to find excuses."
Analysis - Conte downcast but calm
BBC Sport's chief football writer Phil McNulty
Antonio Conte has not had to deal with defeat often in an outstanding first season as Chelsea manager - and none carrying the significance of the loss at Manchester United.
Chelsea's lead over Tottenham has been reduced to four points after this reverse so Conte's response to a setback that has thrown the Premier League title wide open was always going to be intriguing.
Conte's reaction was to deflect all criticism away from his players and take sole responsibility himself.
Time will tell if Conte's approach was correct but it felt the right move. He was downcast but remained calm and his players will surely appreciate and respect his willingness to take sole responsibility by moving front and centre to shield them from the measured criticism that would have been deserved after this rare lapse.
If Conte was frustrated, he hid it well as he spoke of six cup finals awaiting Chelsea in the closing weeks while also underlining how far they have progressed from the struggles of last season and indeed the early weeks of this campaign.
Conte wisely felt his players have given him more than enough this season to allow him to shoulder the burden of the Old Trafford loss and perhaps put them even more in the mood to repay his faith in next Saturday's FA Cup semi-final against Tottenham at Wembley, as well as Chelsea's next Premier League game at home to Southampton the following Tuesday.
The Italian has barely put a foot wrong since setting Chelsea on course for the top of the Premier League after a home loss to Liverpool and a 3-0 beating at Arsenal in September - and he showed plenty of confidence in a squad that still remains title favourites.
|Michael Regan/Getty Images|
MOURINHO FINALLY DELIVERS SIGNATURE PERFORMANCE AS MAN UNITED OPEN UP TITLE RACE
At the 53rd attempt this season, Jose Mourinho delivered a signature performance for Manchester United. For nigh on four campaigns now, the Stone Roses anthem "This is the One" that the players come out to at Old Trafford has less been a statement of fact than a forlorn hope. Finally on Sunday, courtesy of a 2-0 victory over Chelsea, United supporters left the ground content in the knowledge this was the one they've waited for.
It is a result that in all likelihood will prove seismic in neither the title race nor United's bid for a top four place, but nonetheless, it was the first time in a long time Mourinho's side made something happen rather than looking to the heavens and willing it to.
When he swaggered off the field to a rapturous reception, pointedly tapping the club's crest on his left breast, Mourinho did so in the knowledge his players had pulled off the perfect tactical plan. It was a reminder to himself as much as the watching world that when he's good, he's very, very good.
Marcus Rashford was the catalyst. Ably assisted by Jesse Lingard, Robin to his Batman, United finally had some pace and youthful zeal up front. Kapow indeed. Gary Neville was beside himself. Talk of their link-up play being similar to Dwight Yorke and Andy Cole was hopelessly premature, but it's not hard to understand why a died-in-the-wool United fan would get carried away.
When Rashford was replaced by rested top-goalscorer Zlatan Ibrahimovic, it was to an ovation of such electricity Greater Manchester could have been powered for a week had the National Grid plugged into Old Trafford in the 83rd minute.
In overseeing nine Premier League draws at home, Mourinho has not even come close to exorcising the lingering spectres of David Moyes and Louis van Gaal. A stat flying around on Sunday revealed only three other clubs in world football can boast, for wont of a better word, as many home stalemates this season.
Whether apocryphal or otherwise, it's been grim up north. Since Sir Alex Ferguson's retirement, United have been stodgier than a three-month old fruitcake. Here they were fleet of foot yet spiky with it, a cupcake with a concrete centre. Controlled aggression can rally a crowd just as effectively as sublime skill.
Repeatedly they turned Chelsea. Like watching the original of a classic film that has been badly remade by Hollywood, it momentarily restored equilibrium.
Through the rain it felt as if a thick veil of inertia had been lifted. Dust blown off a cupboard. All season Chelsea's shape has drawn more compliments than Marilyn Monroe's. On Sunday, it was bent double, wheezing at the thought of being given a chasing by Tottenham Hotspur having been handed a pasting by United.
Chelsea finished the game without a single shot on target. It took until first-half stoppage time for them to have a shot period.
The fixture list may be kind to Chelsea in their remaining games, but football is nothing if not a cruel master. In just under a month, a 13-point lead has been reduced to just four. With two defeats from their last four matches, Chelsea are starting to look leggy on the home straight.
It's fair to say few predicted Sunday's result when news filtered through of United's teamsheet.
The writer Aldous Huxley once said, "several excuses are always less convincing than one." Mourinho had reeled off so many in the week leading up to the game it was anticipated Ibrahimovic's absence would be attributed to the dog having ate him.
Thursday's trip to Anderlecht had tipped United's air miles in Europe this season to around the 13,000 mark. After scoring against Sunderland last weekend, the Swede had said, "like Benjamin Button—I was born old and I will die young." Somewhat less poetically, his manager explained on Sunday his striker was, "tired—very tired." Benjamin Buggered, perhaps.
Some 19 goals and 16 years separate Ibrahimovic and Rashford. Given United's second top goalscorer Juan Mata has just six, any criticism of a man on 28 and counting seems almost delirious. Yet when he plays, there's no doubt United are one-dimensional to the point of being debilitating. That's not his fault. He is on the PFA Player of the Year shortlist on merit. Still, Sunday hinted a future without him that might not be as bleak as many predict.
On first glance, Mourinho's starting XI, to borrow from Huxley again, promised anything but the Brave New World it ultimately transpired to be. Between them, those selected had scored just 12 Premier League goals all season. It looked like a League Cup team, or maybe one sent by Mourinho to play a close-season exhibition game in a far-flung city no one wants to visit in June.
At a loss trying to work out how United would line up, the solitary note made in my margin was "cowardly selection?" There's a reason people like me make notes and Mourinho is one of the best coaches in world football.
"When it is still mathematically possible to finish in the top four, I think if we play against Chelsea with our second team you would kill me," he had said on Friday. "The football country would kill me."
Under the cloak of anonymity, a fair few Manchester United supporters would probably have been sorely tempted.
In picking the team he did, it all felt a bit like Mourinho was indulging in a "woe is me" routine. If United won with that XI, he'd be pronounced a tactical genius, and if they lost, well, did you see the team he had to pick?
Ashley Young taking the captain's armband off Marouane Fellaini is not a sentence one would expect to type when writing about the most expensive side ever assembled in English football. Both were excellent. Anthony Martial didn't even make the matchday squad after his aberration of a performance in Belgium, while the striker formerly known as Wayne Rooney was nowhere to be seen either.
Henrikh Mkhitaryan made only the bench, while Luke Shaw's reward for some decent displays of late was a place alongside him. Clearly Mourinho thought he would be too busy to manage and play at left-back, as he did so superbly against Sunderland.
Instead, he went nominally with an unorthodox 3-1-4-1-1 formation. Ander Herrera, and to a lesser extent Matteo Darmian, were both handed man-to-man marking jobs on Eden Hazard and Pedro, respectively. Young and Antonio Valencia were pushed into midfield, while Lingard fluttered just off Rashford. For all the stick he gets, Lingard didn't look a million miles away from being a £100,000-a-week player.
A United manager hadn't gone so maverick with a team selection since Ferguson employed twin bothers Rafael and Fabio da Silva as twin wingers in an FA Cup tie against Arsenal in 2011. It finished 2-0 that day, too.
In preventing the league's best player from managing either a shot on goal or a successful dribble, Herrera was immaculate. In each of United's best three results this season, at home to Tottenham and Chelsea and away at Liverpool, he has arguably been their top performer.
As big an irritant (the polite euphemism for little s…) on the pitch as he appears lovely off it, it would not be a surprise if the roaming captain's armband finds a permanent home with the Spaniard next season.
Detailed with a man-to-man marking job as out of fashion as Antonio Conte's baseball cap, he followed Hazard around the pitch as obsessively as Sally does her unrequited love interest Schroeder in Peanuts.
The more pious of Chelsea supporters would argue he got lucky with referee Robert Madley's somewhat lenient manner. However, the sight of Herrera and the generous spirited Hazard exchanging pleasantries at full-time suggested the Chelsea man accepted Mourinho's special Eden Project, on this occasion, fell within the rules. He might have been less understanding when he found Herrera spooning him on Monday morning.
One suspects the only thing Mourinho would have enjoyed more than looking smugly up the touchline at Conte would have been chasing Hazard around the pitch. Had Herrera not performed, his manager would probably have made him walk home in his full kit and boots without a shower.
The midfielder's diligence was perfectly encapsulated late in the first half when after playing the ball wide to Valencia he checked himself and almost immediately ran backwards to get goal side of Hazard. It was such an unnatural movement to make; yet he did it with an urgency that bordered on panic. It was as though he had just realised he had left his bag on a train and was sprinting back for it.
Where United unquestionably did get lucky was in the build-up to Rashford's opening goal in the seventh minute. Madley would have to accept his failure to spot Herrera using his left hand to intercept Nemanja Matic's pass through to Hazard was a poor piece of refereeing. It was one of the few occasions when the Belgian had got the wrong side of his stalker.
Although momentarily liberated, Herrera knew he would have to do something special to escape the wrath of his manager. With a pass that deserved to be set in bronze, he fed the ball through to allow Rashford to engage in a foot race with David Luiz. As was the case all afternoon, there was only ever going to be one winner. With two touches he took the ball out of his feet, before with a third expertly shot across Asmir Begovic, who perhaps had set himself just a touch too early.
Remarkably, it was the first time in a home league game United have scored in the opening 20 minutes. Half the crowd probably dropped a pie or pint on the way back to their seat. For one of the first times this season, Chelsea's high line looked a little kamikaze.
For once Chelsea's point guard N'Golo Kante seemed dwarfed, flustered even. United's midfield never gave him a moment to settle, with Matic's performance alongside him more the corked variety served under Mourinho last season than this term's vintage under Conte. Even Fellaini, usually more Big Bird than Larry Bird in terms of co-ordination, looked quite slinky on his feet in comparison.
Kante was badly at fault for United's second goal. The infectiously pugnacious Young pickpocketed him as he dithered in his own box, before the ball found its way to Herrera on the edge of the area. His drive took a nick off Kurt Zouma on its way past Begovic. Gary Cahill in pulling Lingard up to his feet while all this was going on is probably still trying to dislodge a Conte-sized flea from his ear.
At 19, Rashford was making his 61st senior appearance. Such is his game intelligence, it's easy to forget he's a kid. A beautifully fluid mover, he quickly worked out he had the beating of Victor Moses down United's right. All afternoon he repeatedly tormented a Chelsea back line that missed the in-form but unwell Marcos Alonso, who had ruled himself out just before kick-off, more than anyone could have anticipated.
It will be a concern for Conte if his finely tuned side completely loses its rhythm with just a solitary change among his outfield players. Thibaut Courtois, absent due to an injury picked up in a basketball promotion shoot that Conte is probably just fine about, was missed, but not half as much as Alonso's gilded left foot.
Although Rashford prefers to play centrally, his natural inclination is to drift wide. On the day, he put in double the amount of crosses than any other player on the pitch. Once he perfects that curved run from either side, in the manner of Thierry Henry, he will be even better.
Even more encouraging than Rashford's expected hard running, via an endearing gangly glide, was the physical aspect of his game that so unnerved Chelsea's back three. Fears United would have no one to hold the ball up in the manner of Ibrahimovic proved wholly unfounded.
Even with the added muscle provided by Zouma's late call-up due to Alonso's sickness, Chelsea struggled to contain him. In one memorable slaloming run in the second period, Luiz, twice, and Kante, both bounced off him after going shoulder to shoulder before a low drive was saved by Begovic.
Diego Costa's afternoon's work could not have been more marked. He spent most of the game either arguing or being dispossessed by Marcos Rojo, who was singled out for praise by Mourinho at full-time.
Most people tend to avoid picking fights with Argentinian defenders with tattooed thighs, but then Costa is no ordinary player. He's hit a slump at just the worse juncture for Conte, with the Spain international having scored in just four of 15 games for Chelsea since the turn of the year. Eric Bailly, an equally towering presence alongside Rojo, deserves a nod of appreciation, too.
It was telling in his post-match interview with Sky Sports how much more mature Rashford seemed than in those first few appearances in United's first team last season, when he introduced himself with goals against Arsenal and Manchester City.
A question about how it felt to step into Ibrahimovic's boots was met with steel not a smile, as though it was almost impertinent to ask. He seemed to take exception to the suggestion his team-mate was somehow irreplaceable.
Maybe Mourinho has finally instilled in his players the siege mentality he always craves. In hindsight, the manner in which the club's media commitments were fulfilled pre-match suggested collectively they have tired of repeated accusations of underperformance.
On Saturday, Mourinho had given an interview to Sky Sports' Jeff Stelling. Not once did he come close to breaking into a smile throughout what looked to be a tortuous 10 minutes for both of them. Hostage videos have been released with more merriment.
Shot against a moody grey backdrop, it was impossible to say where Mourinho was being held captive. The only surprise was that he didn't finish the segment holding a newspaper with Saturday's date, before insisting his Sky Sports captors were treating him well.
A day later it was Geoff Shreeves who seemed to get under the skin of Paul Pogba. The Frenchman is never far from breaking out into a beatific smile, only this time it felt more like he was bearing his teeth like a dog might to a warden. He held it for just a little too long.
A grumble over how he felt unfairly maligned in relation to how the press has fawned over his compatriot Kante this season seemed uncharacteristically bitter. When Shreeves turned the topic on to whether extracurricular activities had affected his game, the conversation became about as awkward as a father having an informal chat with his son about condoms.
Shreeves spoke of emojis with the same suspicion in his eyes as religious zealots did denim in the '50s. Thankfully, he felt better of initiating a "stay safe Paul" fist-bump with his interviewee. Or more likely it just got cut.
If United reach the Europa League final this season, they will play 64 matches in total. In the treble winning campaign of 1998/99, they played 63. Achieving a treble of sorts by adding the Europa League to the League Cup they have already won, along with qualifying for the UEFA Champions League, would surely leave everyone associated with the club quietly sated.
It would be like a meal saved by a mind-blowing dessert after mediocre starters and mains. After the fare dished up against Chelsea, Mourinho, his players and the club's supporters will be as confident as they have been at any point all season.
Manchester United striker Marcus Rashford has a glorious future, says Matteo Darmian
Marcus Rashford can become “one of the most important players in the world”, according to Manchester United team-mate Matteo Darmian.
The 19-year-old striker opened the scoring in United's 2-0 win over leaders Chelsea on Sunday as United extended their unbeaten Premier League run to 22 matches.
Rashford has now scored nine goals this term but has been restricted to just 14 Premier League starts due to Zlatan Ibrahimovic's prolific form this season.
"I think Marcus is a great player," Darmian said. "He is still very, very young and I think he is very important for us.
"With his quality, he can be one of the top players, one of the most important players, in the world.
"I think he is very good in every part of the game, he has a very good shot, movement, speed.
"Sometimes for a striker, it is a normal there is a not as good period [in terms of scoring goals] but I hope he continues like this, because it helps the team to reach the objective."
United have a game in hand on fourth-placed Manchester City, trailing their local rivals by four points in the race for Champions League qualification through the Premier League.
The other objective for Jose Mourinho's side this season is to win the Europa League to secure their spot in Europe's premier club competition.
"We know our characteristic," Darmian said. "Sometimes, of course, we draw a lot of games at home.
"We deserve to win a lot of games but sometimes it is not possible to win and we draw.
"We lost a lot of points at home but I think we have a chance with six or seven games to go, so still the possibility in our hands.
"This kind of game [beating Chelsea] gives us confidence. I think everyone is concentrated for this end of the season because we know we play for two big opportunities.
"One is the Europa League and the second is finish in the top four because I think playing in the Champions League is a very good objective for next season.
"We have to fight and try to win as many games as possible."