Blues boss Roberto Mancini immediately replaced the 20-year-old, so unimpressed was he by Balotelli's conduct, leading to a touchline row that heightened fears about a lack of discipline in the City camp.
However, Beckham, whilst reminding Balotelli of his status within the game, did feel there was a legitimate excuse.
"I have watched it back a few times and from his mannerisms I believe he thought he was offside," said the former England skipper.
"Mario has been a great player for quite a few years and he is still very young. He will continue to get better I am sure.
"But it doesn't matter whether you think it was offside or not. There are a lot of young kids watching these teams and great players who come out here.
"You have to be professional and score the goal."