The former England captain came close to joining Tottenham Hotspur on loan in January but a move fell through towards the end of the transfer window.
The LA Galaxy midfielder, whose contract with the MLS club expires in November, admitted that he can't see himself lining up against his former side.
"I have always said that I have played for the biggest club in England and I wouldn't like to play against them," said Beckham.
"I am 36 and still feel good and fresh but I can't see it happening.
"The Tottenham thing didn't happen for a reason. I only want to be known as a Manchester United player, and that's the way it will stay."
Beckham spent ten years at Old Trafford, making 265 Premier League appearances.