Iran fired on an unarmed U.S. drone last week as it was hovering in international airspace, the Pentagon announced Thursday.

Spokesman George Little said the incident, which marks the first time the Iranians have fired on a U.S. drone, occurred Nov. 1 at 4:50 a.m. ET. He said the unarmed, unmanned drone was conducting "routine surveillance" over the Persian Gulf when it was "intercepted" by Iran. He said the MQ1 Predator drone, which was not hit, was not in Iranian airspace.

According to Little, two Iranian jets fired twice, missing on both attempts -- the drone headed away from the Iranian coast, landing safely soon after at an undisclosed location. The Iranian jets pursued the drone for a short period before giving up.

Little said the U.S. government has protested to the Iranians. Asked about how the U.S. could respond, he said: "We have a wide range of options from diplomatic to military."

He would not say whether there were actually plans for a military response. Asked if this should be considered an act of war, Little said he didn't want to get into "legal characterizations" of the event.

Little stressed that the drone was flying 16 nautical miles off the coast of Kuwait in international waters, and never entered the 12-mile limit that would constitute Iranian territory.

The Pentagon announced the incident as the administration imposed a new round of financial sanctions against Iranian officials and entities. They marked the first sanctions since President Obama's re-election Tuesday. According to the Treasury Department, the move was "related to the Iranian government's human rights abuses, its support of terrorism and Iran's Islamic Revolutionary Guard Corps."

The drone encounter comes after a U.S. drone crashed in Iran late last year. Iran claimed to have shot it down, but U.S. officials said it merely malfunctioned and crashed.

Little said the U.S. will continue to run surveillance missions in the region.

Fox News' Justin Fishel contributed to this report.