The department issued an alert Thursday. It's stepping up existing advice for Americans to be aware of the risks of travel to Pakistan and said they should defer all non-essential travel to the country. It says protests and demonstrations, some targeting U.S. interests, are likely to continue.
The warning comes as hundreds of Pakistanis angry at the film clash with police in the capital. A crowd of more than 1,000 people tried to make their way to the U.S. Embassy inside a guarded enclave that houses embassies and government offices.
Riot police used tear gas and batons to keep stone-throwing demonstrators away.