The England midfielder joined Milan from LA Galaxy on a short loan deal that is due to expire in March.
He made an immediate impact, scoring twice in four appearances and putting in some assured displays in Milan's three-man midfield.
Reports suggested Beckham would prolong his stay at the Italian giants although he recently said he was undecided whether to continue his Italian adventure.
But Leiweke said there was no chance for the 33-year-old to remain a Rossonero.
"Beckham is under contract to the Galaxy and I had a good, straightforward conversation with him before he left and he loves it in LA," he told Los Angeles Times.
"We have a contract, we have a handshake, and his kids go to school here, end of story. There is no story. He's going to return to Galaxy.
"He wants a better Galaxy team, we're going to have a better team and David has no interest in going."
Watch Beckham's goals with Milan