Goals from Marcus Rashford and Ander Herrera condemned the Premier League leaders to a 2-0 defeat against Mourinho's Manchester United and left them just four points ahead of Spurs with six games to play.
Chelsea led the table by 10 points at the start of April and Conte, whose side were also beaten by Crystal Palace a fortnight ago, accepted the blame for the latest slip-up and admitted Spurs are back in the title race.
The Italian said: "I think that the impact was very tough today, but when you play at Old Trafford it is normal to have this type of impact against a really strong team as United.
"We didn't play a good game and United deserved to win the game. They showed more desire, more ambition, more motivation to win.
"It is very simple, but in this case the fault is of the coach. It means the coach wasn't able to transfer the right concentration, desire, ambition to win this type of game.
"Against Crystal Palace we didn't deserve to lose, but today we deserved to lose the game.
"We have to think that there are six finals from now until the end. The league is open and we have a 50 per cent probability to win the league.
"We will be good to finish on top of the table and it means we deserve this. Otherwise we deserve another thing."
He added: "I think Tottenham now are the best team, they are in good form and have a lot of enthusiasm. They are feeling the possibility to write history."
Conte insisted the pressure would not get to him.
He said: "The pressure is normal. I prefer to play for the title instead of don't fight for the title and stay calm. We are lucky to have the pressure.
"Last season Chelsea had no pressure - 10th place and you play calm, and you are happy.
"We must have great enthusiasm to play these last six games, with patience and a great will to fight.
"If we are able to win I think we must be proud for this, otherwise we must clap another team."