The 23-year-old only left the Premier League and Manchester City in January, for a fee of £19million, but rumours have begun circulating that he could be reunited with his former Inter Milan boss Jose Mourinho at Stamford Bridge.
But Allegri told AC Milan’s official website: “”He will not leave in January. Absolutely not. I think Mario should be left in peace. It’s not difficult to manage him.
“There’s far too much discussion of the man’s private life. I think that Balotelli should be judged for what he does on the pitch like all other players.”
The controversial striker has rediscovered his best form since returning to Serie A in January, although he reacted angrily to being substituted during Sunday’s 3-2 defeat at Parma.
“It happens that players play badly but if you are Mario then everything is blown out of proportion,” Allegri added.
“Mario didn’t play well against Parma but I’m sure he will make amends against Lazio. He scored 12 goals in 13 games last year.
“In the first half of the season he has done great things.”