Beckham is currently on loan at Milan from Los Angeles Galaxy, and the English international is set for a summer return to Galaxy before rejoining the Rossoneri next winter.
An agreement was reached between the three parties that Milan will pay Galaxy £5 million, before Beckham buys out the remainder of his contract for another 5 million in November 2009.
However, reports from Italy and Spain suggested that if installed as Real Madrid president, Florentino Perez might launch a £10 million summer bid to lure Beckham from Galaxy.
"That seems really unlikely to me. Beckham will play the second semester of this year in Los Angeles," Galliani was quoted as saying by Football Italia.
"An offer for January 2010 just isn’t going to happen, I really wouldn’t bet on it."
Alongside Zinedine Zidane, Luis Figo and Ronaldo, Beckham was part of Perez's galacticos when the latter was Real president between 2000 and 2006.
"I don’t know everything Perez does, but first of all he has to become the President," added Galliani.
"It all seems very strange to me. No, if I were a betting man, I wouldn’t say that Perez would sign Beckham."