The Marine Corps said the actions portrayed in the clip, which was posted online but has not yet been verified, were not consistent with its values.
The footage shows four men in military fatigues appearing to urinate on three apparently lifeless men.
A man’s voice is heard saying: “Have a great day, buddy.”
The origin of the video is not known, nor is it clear who posted it online.
The men in military fatigues seem aware that they are being filmed.
Pentagon spokesman Capt John Kirby said in a statement: “We are deeply troubled by the video.
Afghan Member of Parliament Fawzia Kofi said ordinary Afghans, no matter how they felt about the Taliban, would be upset by the video.
“I believe that the brutal acts that the Taliban did here during their government and even now is condemned by Afghans. So is watching a brutal act by international forces. We condemn that as well,” she added.
The Council on American-Islamic Relations (Cair) said the video, if verified, showed behaviour that was totally unbecoming of US military personnel.