VIENTIANE (Reuters) - President Barack Obama said on Tuesday his push to rebalance U.S. foreign policy to focus more on Asia was not "a passing fad" of his presidency and, in a clear reference to China, said bigger countries should not dictate to smaller ones.

"I've worked to rebalance our foreign policy to make sure America is a key player in the region," Obama said in a speech on the sidelines of a summit in Vientiane, Laos.

He also said that a failure to move ahead with the 12-nation Trans-Pacific Partnership trade pact would "call into question America's leadership".

"I think it is important for the entire region and it is important for the United States," he said.

(Reporting by John Chalmers; Editing by Robert Birsel)