The Italian striker returned from international duty with a thigh problem, with some reports suggesting he could be out for up to three weeks.
Galliani also announced that goalkeeper Christian Abbiati is expected to miss the visit of the Spanish champions, although Marco Amelia should deputise despite Brazilian youngster Gabriel keeping a clean sheet against Udinese.
"I have total faith in Professor Enrico Castellacci, so if Italy allowed [Balotelli] to play then they must've been convinced he was fit," the 69-year-old told Sky Sport Italia.
"From what our staff tell us, it will be very difficult for Balotelli and Abbiati to recover in time for Barcelona on Tuesday."
Barca have won both of their games to top Group H with the Rossoneri two points behind them in second.