Mancini blamed Hart for the spot-kick, which he saved, and told him to strive to be "perfect" in future.
Mancini said: "Joe is the best keeper in England and one of the best in Europe.
"I'm pleased he saved the penalty but a keeper like him can do better.
"When the long ball comes, he should be there.
"I want him to be perfect and he could be if he wants. He is the best."