WASHINGTON (Reuters) - The White House on Wednesday said Iran's role on Syria has not been productive and the United States was interested in working with nations that would be more constructive in helping bring stability.

U.N. envoy Kofi Annan has said Iran should play a role in peace talks on Syria. White House spokesman Jay Carney said while he was not ruling anything out, "we reject the idea that it is likely that Iran can play a constructive role."

Iran is seen as a key supporter of Syrian President Bashar al-Assad's government which has been engaged in a bloody battle against opposition forces since an uprising began in March 2011.

"Iran's role has not been productive or helpful. Our interest is in working with nations who want to see stability in Syria," he said.

Carney said there had been a number of high-level Syrian defections recently, including from Assad's inner circle, which indicated "support for Assad is crumbling." But he said he could not confirm the latest reports of the defection of Syria's ambassador to Iraq.

"There have been a number of high-level defections in recent days and weeks and they are simply the tip of the iceberg, there have been many, many defections within the military leadership, within the government," Carney said.

(Reporting By Tabassum Zakaria and Alister Bull; Editing by Eric Walsh)