The Rossoneri director has stressed the importance of concentrating on the club's next two league games and securing a top three finish in Serie A.
The San Siro side takes on Lazio at the weekend and also meets Genoa before the return European fixture at Camp Nou, and Galliani has urged Massimiliano Allegri's men to concentrate on their domestic duties.
"We cannot think about Barcelona now as we have two games to win first against Lazio and Genoa," Galliani was quoted as saying on the official Milan website. "The next round of games will be an important one. It's first against second as well as third against fourth. Except for Fiorentina, they're all in action.
"There are many teams going for third. Us, Lazio, Inter, Fiorentina, Catania, Roma. Six teams for third. It's a league within a league."
Milan currently sits fourth in the league table with 45 points from 26 games and beat Barca 2-0 in the first leg of their Champions League tie.