Mancini would not confirm that his comments applied to two controversial penalties awarded to Manchester United at Old Trafford in recent weeks.
But what he did say was that some of "the situations" had made City's hopes of lifting the title for the first time in 44 years "really difficult".
When asked to elaborate he told a news conference: "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."
Asked if he was suggesting the rules are different for City and United, he replied: "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 [in England] there were the best referees. My idea has changed, probably."
United are five points clear of City with four matches to play and have beaten both Queens Park Rangers and Aston Villa at Old Trafford in the last two weeks with Ashley Young earning penalties after theatrical falls in both games.
United manager Sir Alex Ferguson said on Friday he had "had a word" with Young about his antics, but that does not help Mancini's situation.
Speaking at his pre-match briefing before Sunday's visit to bottom-of-the-table Wolverhampton Wanderers, Mancini said he did not think City had any hope of winning the title although his players felt otherwise.
"I am happy because they believe but, for me, I [still] have the same feeling. I think it will be very difficult.
"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."
City won 6-1 at Norwich last week to keep alive their title challenge although United remain favourites to retain their crown and become champions of England for the 20th time.
