The Italy international was dismissed 18 minutes after coming on as a second-half substitute for two bookable offences. Mancini had no argument with the first, for pulling back Glen Johnson, but was adamant the second for catching Martin Skrtel with an arm was unjustified.
"It is not correct, the [second] yellow card. I do not agree with this yellow card," said the City boss. "The referee didn't want to get a yellow card out, he did nothing for the yellow card.
"I think every time Mario does something many players provoke him. I think the referee gave a free-kick, but didn't want to give a yellow card until all the Liverpool players complained. I watched the replay and for me it is nothing.
"This situation in the Premier League - there are a lot in every game; I don't think all are yellow cards. He moved his arm and Skrtel was like a young player and I don't think that was good. Mario should pay attention because he knows many players provoke him and this is not correct."