Mancini did not want to comment on specific incidents but title rivals Manchester United have benefited from two controversial penalty decisions in the past fortnight, while City were left feeling wronged when striker Carlos Tevez was harshly booked for diving in last week's defeat of Norwich.
With four games remaining and City trailing United by five points, Mancini alluded to the refereeing decisions having an impact on their title hopes, saying: "After some of the situations I saw in the last three or four weeks, I think it is really difficult for us."
He has already said his side's title hopes are over, and still feels that way despite some of his players expressing a different opinion.
When asked his thoughts on what his players have said, Mancini said: "I am happy because they believe but, for me, I (still) have the same feeling. I think it is very difficult."
Mancini, at a press conference to preview Sunday's game at Wolves, was then asked to elaborate on his suggestions about the standard of refereeing.
He said: "I can say it is a very strange situation, only this. For us it is important to finish well this season. We want to try to win the next game. That will be difficult. Wolves are bottom of the table and it will be a tough game. We need to play like against Norwich."
When asked to expand again about these "situations", Mancini said: "I am not frustrated. In Italy we say, 'Every place is the same'."
Asked what that meant, he said: "The rules are not the same for everyone."
Mancini was then asked if he was suggesting the rules are different for City and United, and he said: "I am not saying this, I don't want to say this. I said the rules, maybe sometimes, are different. When I was in Italy I always thought here there were the best referees. My idea has changed, probably."