The Italy international has been out of favour at the Etihad Stadium following his lacklustre display in the derby against Manchester United and was recently pictured confronting manager Roberto Mancini during a training session.
With the January transfer window now in full swing, the former Inter Milan players has been linked with a return to Italy, but Galliani has again ruled out a move for the striker.
He told Sport Mediaset: "If no-one leaves, no-one will arrive.
"Mario Balotelli? We have five strikers for two/three roles, so we are fine.
"I always said that if only one striker were to leave, we would not have taken anyone, and we have sold only Pato.
"AC Milan needs a bit of time to get back to the top, but I'm sure we will. We want to invest in young players also in this market window."