Sources told ESPN FC that the celebrations following the victory at Old Trafford were "very vocal" and accompanied by loud music, prompting a confrontation between players and staff from both clubs.

The Football Association has since written to both clubs to seek their observations over a reported tunnel bust-up but Guardiola said the celebrations were not over the top.

"If we were not correct than I apologise to all of Manchester United -- our intentions was not that," Guardiola told a news conference. "It was to celebrate inside the locker room. If the people cannot understand that then I'm sorry.

"We won a derby -- if we offended United -- not just one player, not Jose [Mourinho] -- Manchester United, then I apologise. Sometimes United made a lot of celebrations in the past over City. All the managers celebrate sometimes and exceed. But it didn't happen. We have to enjoy those moments."

The City squad also applauded their victory on the pitch with the away fans but Guardiola decided to return to the dressing room, despite his backroom staff encouraging him to celebrate with his players.

The Catalan said it is important for his team to acknowledge the supporters -- as clubs regularly do in Germany -- but said he is reticent to go on the pitch now following the controversy over his exchange with Southampton's Nathan Redmond last month.

"I did the ridiculous thing with Redmond. I don't want to do that, believe me, but sometimes you do," he added. "Sometimes you can control yourself and say 'OK, it's not necessary to go there.' We haven't won anything so we went in the locker room.

"You discuss if it's a penalty or not football -- that's part of football -- and after we go to the locker room.

"To celebrate with your fans is part of it. In Germany everyone goes over if you win or lose. I said when I arrived that winning or losing, you have to go over when you are away to say thank you. The last action was in the corner and we celebrated there in a normal way -- nothing exceptional."