US claims leaked documents could put diplomats and others in danger as it scrambles to contain damage.
The White House says it may take legal action after the WikiLeaks website published hundreds of secret memos sent by US embassies.
The messages reveal growing concern over Iran’s nuclear ambitions, with Saudi Arabia pushing the US to act.
There are also unflattering remarks about the leaders of America’s European allies, and apparent suspicion of the UN.
Al Jazeera’s Mike Hanna reports from the US state department.