Kevin De Bruyne netted a 70th minute winner as the Sky Blues moved 13 points clear at the top.
Liverpool can close the gap to 11 points when they play Brentford on Sunday but City’s margin is significant.
It is an important victory because we are playing against a big contender,” Guardiola told reporters.
He added: Of course because when you get three points, they cannot get three points and its one week less.
In January, no-one is the champion. We can think about Chelsea, but Liverpool have one game in hand (after they play Brentford on Sunday).
If they they win (the game in hand) versus Leeds, its eight points and eight points in January is nothing. We spoke before the game.
I want to win the game if we deserve it and we deserved it. I like football to be fair. I was happy to win against Arsenal, but we didnt deserve it. When you deserve it, it feels better.
The result leaves the Red Devils five points outside of the top four positions, with fourth-placed West Ham United playing Leeds United on Sunday.
Wolverhampton got the better of Southampton 3-1, while relegation battlers Newcastle and Watford drew 1-1.