Ilkay Gundogan insists it was wrong to award the free-kick that led to Manchester United's opening goal in the derby and has accused Bruno Fernandes of play-acting.
City midfielder Gundogan was penalised when he prodded the ball away from Fernandes while making minimal contact with the United star 29 minutes into the match at Old Trafford.
Ole Gunnar Solskjaer's side took the lead from the resulting set-piece, Fernandes chipping a clever pass that Anthony Martial volleyed past Ederson.
United withstood City pressure in the second half before Scott McTominay pounced on another Ederson error to secure a 2-0 victory in second-half injury time.
"There was frustration about the free-kick before the goal," Gundogan admitted. "It was not a foul at all. I just touched the ball and he goes on the floor shouting.
"I don't even know if the referee saw it or just had a feeling that it was a foul. That was very disappointing for me, to be honest, because I was involved in the action and conceding the goal straight afterwards hurt very much. We tried hard after conceding the first one but it just wasn't enough."
Gundogan refused to pin blame for the defeat onto Ederson, who also nearly allowed Martial to score a second with uncharacteristically careless control.
"Eddy has been crucial in so many games for us, and he is allowed to make mistakes. Unfortunately, this time they were punished, very crucially for us," he said.
"We win together and lose together. That's why we play football; that's why we're a team. He will deal with that situation very well. He's angry, disappointed and frustrated, but it's always about how you get out of it. He has all of our support and I'm sure he will do much better in the next games."
City could not match United's intensity in the first half and were short on creativity in the absence of Kevin De Bruyne, managing only four shots on target throughout.
"It hurts a lot," said Gundogan. "Not really the result but that we didn't play our best game, especially creating in the last third. This game is always big, one of the biggest derbies in the world. That's why we wanted to perform and play well.
"United were much more aggressive, especially after scoring the first goal. They tried to press very high for 10 minutes afterwards. Missing Kevin is crucial in these kind of games.
"But we still have some very important games, big games. We play Arsenal now and Burnley. Then obviously a vital game against [Real] Madrid at home [in the Champions League] and another crucial game in the FA Cup.
"So we still have the possibility to win silverware. We will try to achieve that and do better than we did on Sunday."