The Los Angeles Galaxy midfielder had been widely expected to win selection as one of the three over-age players in Stuart Pearce's Under-23 squad for the London Games in July and August.
"Naturally I am very disappointed, but there will be no bigger supporter of the team than me," Beckham, 37, said in quotes relayed by his spokesman on Thursday.
British media reports said Manchester United's long-serving Welsh winger Ryan Giggs, Wales striker Craig Bellamy and Manchester City right back Micah Richards, who missed out on England's Euro 2012 campaign, had been chosen.
An official explanation for coach Pearce's decision has yet to be issued by the Football Association (FA).
The FA will hand a final team list to the British Olympic Association (BOA) early next week.
"As with every sport, player selection is the responsibility of the National Governing Body, the coaches and performance personnel," a BOA statement said.
"With respect to men's football, the BOA has not yet received from The FA the list of players who are being nominated for Team GB, so we cannot confirm who is, and is not, under consideration for the side. We are expecting the list no later than the early part of next week."
Beckham, who has played for Manchester United, Real Madrid and AC Milan in a glittering（闪闪发光的） career, was watched by Pearce during a recent match for the Galaxy and was included in his initial 35-man squad.
Beckham told reporters last month: "I don't want to be picked on a shirt sale or a stadium filler. I want to be picked because of what I can bring to the team."
Beckham was England's most capped outfield player with 115 appearances but has not played for the national team since 2009.
The world famous trend-setter now misses the chance to captain an England side at World Cup, European Championship and Olympic level.