Kerry says Iran vow to defy US is 'very disturbing'

US Secretary of State John Kerry said a speech by Iranian Supreme Leader Ali Khamenei on Saturday vowing to defy American policies in the region despite a deal with world powers over Tehran's nuclear programme was "very disturbing" .

Secretary of State John Kerry, accompanied by Secretary of Treasury Jack Lew, and Secretary of Energy Ernest Moniz, testifies before a Senate Foreign Relations Committee hearing on Capitol Hill, in Washington (AAP) Source: AAP

"I don't know how to interpret it at this point in time, except to take it at face value, that that's his policy," he said in the interview with Saudi-owned Al Arabiya television, parts of which the network quoted on Tuesday.

"But I do know that often comments are made publicly and things can evolve that are different. If it is the policy, it's very disturbing, it's very troubling," he added.