The State Department warned U.S. citizens around the world to be alert to "the continued potential for terrorist attacks."
"Current information suggests that al Qaeda and affiliated organizations continue to plan terrorist attacks both in the region and beyond, and that they may focus efforts to conduct attacks in the period between now and the end of August," the State Department said in a statement.
Details about the threat were not released, but officials believe the possible attack will occur or come from the Arabian Peninsula.
A senior official tells ABC News there's an "active plot" coming from al Qaeda in Yemen. Yemen is where the so-called "underwear bomber" got his training and where radical American cleric Anwar al-Awlaki directed terrorist attacks until he was killed by a drone strike two years ago.
Intelligence shows the new boss, Nasir al-Wuhayshi, is plotting to hit multiple targets inside and outside the country.
"We've had a series of threats," said Rep. Ed Royce, R-Calif., chairman of the House Foreign Affairs Committee. "In this instance, we can take a step to better protect our personnel and, out of an abundance of caution, we should."
On Thursday, the U.S. announced it was closing 21 embassies and consulates from Mauritania in northwest Africa to Afghanistan on Sunday, which is a business day in Muslim countries. The facilities may stay closed for more than a day, officials said.
A major warning was issued last year informing U.S. diplomatic facilities across the Muslim world about potential violence connected to the anniversary of the Sept. 11 terrorist attacks. Dozens of American installations were besieged by protests over an anti-Islam video made by an American resident.
In Benghazi, Libya, a U.S. ambassador and three other Americans were killed when militants assaulted a diplomatic post.
The Associated Press contributed to this report.
