In a notice on the U.S. State Department official website, the agency is advising Americans worldwide, "and especially in the Middle East," to "exercise increased caution."

"Americans abroad should follow the guidance in security alerts issued by the nearest U.S. embassy or consulate," the statement reads.

The State Department is warning that U.S. diplomatic facilities, including those outside of the Middle East, "have been targeted."

The agency warns that groups in support of Iran "may target other U.S. interests overseas or locations associated with the United States and/or Americans throughout the world."