The Rossoneri appeared to be on the verge of dropping two vital points in the Champions League race until Balotelli's late winner, before the striker celebrated the invaluable goal by removing his shirt.
Galliani expressed his delight at the 22-year-old's run of nine goals in 10 Serie A matches, but indicated he will be fined a nondisclosed amount for his antics.
"As long as he scores more goals than the shirts he takes off then that is OK... But taking your shirt off is not acceptable and he will notice that it isn't acceptable on his handsome payslip at the end of the month," Galliani told reporters.
"We are very happy with Mario, though. He is a Milan supporter and that helps, it gives him something extra. He told me that in 1999 he was going around Brescia with a Milan flag in celebration of [Alberto] Zaccheroni's Scudetto."
Balotelli's solitary strike on Sunday moved Milan four points clear of Fiorentina with just three games to go in the battle for third place.