Pellegrini confronted Swedish referee Jonas Eriksson after the final whistle to express his displeasure following City's 2-0 Champions League defeat. He claimed he was not impartial.
"It was just to tell him that I was not very happy because he decided the game," said the City manager.
Barcelona midfielder Cesc Fabregas was pleased the Spanish giants could "prove a point" to some of their doubters following a dip in form over the last month and he was delighted they could "shut up" their critics.
Chelsea boss Jose Mourinho had called the Catalan side "the worst Barcelona of many years" and former Arsenal star Fabregas told ITV:
"Maybe we had to prove a point in a way and I think we did it and I think we did it in a style and very, very well, but this team has done so much and won so much to always have to prove a point.
"But today was one of those days maybe everyone was saying Barcelona was not the same Barcelona...some people were talking a bit too much and as usual they will have to shut up for a few days.
"We are top of the league, we had a good result and we are in the final of the [Copa del Rey]. There's nothing else you can ask for.
FIFA's referees chief has come to the defence of Swedish official after he was accused by Manuel Pellegrini of favouring Barcelona.
Pellegrini accepts his side face a tough task against Catalans in their Champions League last-16 tie, but he is far from intimidated.
Manchester City host Barcelona in the first leg of their Champions League last-16 tie. Here is a look at some of the likely key battles.