Problems over building a stadium were the main reason New York's plan to host the 2012 Olympics failed, the man behind the US city's bid said.
Organisers had to revise their plans after state funding for the original stadium was rejected last month.
"You can't have a glaring weakness with your most important venue and expect to win," said bid leader Dan Doctoroff.
New York were eliminated in the second round of voting - with London picking up a tranche of key votes as a result.
The city's mayor Michael Bloomberg wished London well after the surprise result.
"On behalf of all New Yorkers and New York's Olympic bid, I extend my sincere congratulations to London.
"London is a tremendous city and will undoubtedly host a superb Games in 2012."
A big screen TV set up in the middle of Rockefeller Plaza in New York broadcast the vote from Singapore.
The city had been bidding to host the Games for the first time and Bloomberg said it had benefitted despite the result.
"It made our city better. It heightened the city's Olympic spirit and catalysed important city projects.
"From new parks to new pools, New Yorkers have already benefited from our bid for the 2012 Games."
He said it was too soon to say whether the city would try again for the 2016 Olympics.
"I thought now was the time, we had everything going for us - the spirit, the money, the land was available. It was a unique opportunity for the city of New York," he said.
His comments were echoed by Doctoroff.
"You can never say never, but like the mayor, I believe we had a fantastic combination of forces in our favour right now," said the bid leader.
"This was our moment, but whether or not to bid again is for another day."
Dan O'Brien, Olympic decathlon champion in 1996, said he was "disappointed" that New York did not win but said the campaign would provide useful experience.
"You have to lose one before you win one. All of this will make us much stronger," he said. "This probably
makes us the front-runner for 2016."