The incident occurred during an exhibition match between the L.A. Galaxy, Beckham's current team, and A.C. Milan, with whom Beckham played earlier this year. After Beckham said he wanted to remain overseas past the expiration of his loan, Galaxy fans treated him in a hostile manner during his first game back in the U.S.
With the L.A. "Riot Squad" — a group of confrontational fans — getting on his case, Beckham attempted to climb into the stands at halftime before security stopped him.
"We support our players interacting with fans, whether it is at clinics, charity events or by high-fiving their supporters in the stands while celebrating a goal," commissioner Don Garber told the AP. "However, our players should never engage in conduct that can be interpreted as encouraging fans to come out of the stands and onto the field, regardless of the reason."
Despite the embarrassing nature of the entire sequence of events, Beckham refused to apologize following the game.
"It's not a setback for myself," Beckham told CBSSports.com on Thursday. "It's other people that have to change. It's not about whether I can move on. I wasn't the one booing.
"Of course, I don't like my son seeing that and hearing that. From an organized group of fans, I think it was disrespectful."
The Riot Squad released its own statement through its Web site, claiming that Beckham was mostly to blame for the incident.
"Had David responded differently on Sunday, the booing and the chanting probably would have ended at halftime," the statement said. "We don't believe questioning Beckham's commitment to our team is over the line, but it's clear that David feels otherwise."
Despite being formally "punished" by the MLS by means of a fine, Beckham's wallet won't be getting too much lighter. The $1,000 penalty represents only 0.002 percent of Beckham's $50 million annual salary — not including endorsements.