Balotelli was in fine form for Italy at the European Championships, scoring three goals including a notable brace against Germany in the semi-finals.
Mancini has said that he decided to keep Balotelli because he thinks that there is much more to come from the 21-year-old.
The City boss said: "This summer, we had a lot of requests for Mario, many important teams wanted him.
"I said no because he is young and we are sure he can improve."
Balotelli scored 13 league goals for City last season to help the club win the Premier League title.