Speaking in an interview with PBS, Obama said, "I think that people are justified in being disappointed about the outcome in Copenhagen."
He also admitted that the non-binding agreements reached at last week's climate change talks didn't "move us the way we needed."
He said that he was at least able to secure non-binding agreements India and China.
"We were able to at least agree on non-legally binding targets for all countries - not just the United States, not just Europe, but also for China and India, which, projecting forward, are going to be the world's largest emitters," he said.
Obama said he was unable to get leaders to commit to a deadline of 2010 for a legally binding international climate change treaty.
Obama's comments follow China's rejections of claims made by a British minister that it "hijacked" efforts to reach an agreement at the climate summit in Copenhagen.