The grainy film showed what looked like a Predator drone, a type the U.S. military uses for reconnaissance and attack missions, flying high above unidentifiable territory.
A voiceover in Farsi said "this is an American drone." It said it had been identified by an Iranian drone which was monitoring it undetected.
The video's authenticity could not be verified.
The footage emerged as tensions grow between Washington and the military alliance that backs the Syrian government, including Iranian-backed forces such as Hezbollah.
The alliance threatened on Wednesday to hit U.S. positions in Syria, in response to a U.S. strike on Tuesday against what Washington said were pro-government forces.
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