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Eden Hazard scored a hat-trick as the Blues beat Newcastle 3-0 to move top.
Mourinho said on Monday his side were "the little horse" in the title race.
But on Saturday he said: "It's time to kill the horses," adding, "Manchester City is a Jaguar. You cannot put an 'L' plate on a Jaguar."
Mourinho, who spent almost £48m bringing in new players in the January transfer window, once again played down his side's chances of winning a first Premier League title since 2009-10, despite seeing his side extend their unbeaten run to 10 league games.
They also boast the best defensive record in the division, having conceded only two goals in their previous nine games, and were rarely troubled against Newcastle.
The win meant Chelsea went one point clear at the top of the table after leaders at the start of the day Arsenal lost 5-1 to Liverpool, while Manchester drew at Norwich.
"We were winning 2-0 at half-time but I was not happy with that because I didn't like the way we played in the first half," added Mourinho.
"I was concerned about the details of our game which will be more important in the long term, rather than the result of the game.
"We are happy with what we are doing and at this moment in time we are top. That is great, but we want to play well and improve and that is it.
"I want to secure a Champions League position and the further we are from fifth place, then we can begin to think about other things. For now, my concern is increasing the gap between ourselves and fifth."
Chelsea boss Jose Mourinho compared Manchester City to a "Jaguar" car as the Portuguese suggested Manuel Pellegrini's side are favourites for the Premier League title.