City took the lead through Gary Cahill’s own-goal, but after Kevin De Bruyne saw a close-range shot flick off the bar and over, Chelsea scored through Diego Costa, Willian and Eden Hazard.
Guardiola said: “I say congratulations to Chelsea, but I’m proud of the we played, and we cannot forget against which team we played.
“We created more chances that we did in the games against Crystal Palace and Burnley.
“They have few chances and they scored from them.
“In the boxes we are not strong enough... especially here at home. The opponents, when they arrive they score, when we arrive sometimes not, mentally that’s tough.”
The game finished in an ugly manner, with Sergio Aguero sent off for a challenge on David Luiz and Fernandinho shortly after for his part in the resultant melee.
Guardiola said: “It’s a pity it finished like this, I don’t like that, I apologise for what happened.”
The home crowd felt referee Anthony Taylor did not help City on the day with a series of controversial decisions but Guardiola was clear as to why Chelsea left with the points.
The boss added: “We didn’t win because we missed a lot of chances not because of the referee.”
