The former Inter Milan man has been linked with a return to the San Siro this month after finding his chances limited under manager Roberto Mancini.
Club president Silvio Berlusconi made a public apology after labelling Balotelli as a "rotten apple" during the Ballon d'Or ceremony last week and said the club has no interest in the Italy international.
And Galliani has backed the Rossoneri owner by again dispelling any thoughts of a potential bid for the 22-year-old by telling Sky Sports Italia: "Berlusconi is right about Balotelli. We have never spoken to him and I don't think he is for sale anyway."
Meanwhile, Napoli sporting director Riccardo Bigon admits the chances of the forward joining the San Paolo club is highly unlikely.
"We thought about bringing him here two years ago, but then Mario decided to sign for City," he said.
"Now, everything is different and we're good in attack, so maybe a move could be something that could happen in the future."