Beckham's Galaxy teammates and coach were puzzled by Stuart Pearce's decision not to call the 37-year-old up for the Olympics.
The 37-year-old made an outfield record of 115 appearances for England, captain for nearly 60 of those caps.
"Everyone knows how much playing for my country has always meant to me, so I would have been honored to have been part of this unique Team GB squad," Beckham said in a statement. "Naturally I am very disappointed, but there will be no bigger supporter of the team than me. And like everyone, I will be hoping they can win the gold."
Beckham made no secret of his desire to play for England once more – his last appearance came in 2009 – in his home city. His LA Galaxy teammates sympathized with the former Manchester United and Real Madrid midfielder.
"We're disappointed for David," Landon Donovan said. "You look at it in a bigger context, the opportunity to play an Olympics in your home country is really special. To have that taken from you is devastating, especially for a guy who has done so much for the sport in that country. It doesn't really make sense."
Robbie Keane, who only recently returned from captaining the Republic of Ireland at Euro 2012, said the decision caught all of Great Britain by surprise.
"The whole country was probably thinking that it was 100 percent that he was going to be picked," Keane said. "Everyone is shocked."
Team GB coach Stuart Pearce flew to the United States to evaluate Beckham after including the Galaxy midfielder in his 35-man shortlist. Only allowed three overage players, reports suggest Pearce opted for Ryan Giggs, Craig Bellamy and, surprisingly, Micah Richards.
The decision to snub Beckham wasn't down to fitness, claims LA coach Bruce Arena.
"David's physically fine and he's just getting better," the former U.S. national team boss said. "Over the last two months he's really started to come into form. There's absolutely nothing wrong with him."
Beckham is joint-third in MLS with five assists. Recently he helped turn around a disastrous start to the season, which saw the Galaxy last in the Western Conference, to motor into a playoff position.
"It'd be easier to understand if he wasn't playing well, but I think any body who's seen him play would say he deserves to be on the team," Donovan said.
Additional reporting contributed by Alex Labidou in Miami.
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