It follows rumours spread by supporters of the far-right QAnon movement blaming far-left “antifa” members for deliberately causing devastating wildfires seen this month.
The 32-second clip showed the Democratic presidential nominee Joe Biden speaking in Delaware earlier this week, as graphics depicting so-called “antifa” activists blow-torched the grassland behind him.
The two animated “antifa” men wore helmets with the main “antifacist action” logo, which is recognisable by its red and black flags.
An animated blaze then burns in the background, as Mr Biden addresses the climate crisis and wildfires across Washington, Oregon and California.
“Trump’s climate denial may have not caused these fires,” said the Democrat, “but if he gets a second term, these hellish events will continue to become more devastating”.
After Mr Biden’s voice is drowned-out by sound effects, the video ends with him asking “Do you know what is actually threatening our suburbs?”
An “Antifaschistische Aktie” logo then appears, in an apparent reference to the Communist militant organisation that operated in Wiemar Germany.
The video ends with a message saying: “You just have to look it up, Mr Biden”.
Authorities have been inundated with calls about those claims, with the Sheriff's Office in Douglas County, Oregon, warning that "Rumours spread just like wildfire".
In a statement, the office said dispatchers had been "overrun with requests for information and inquiries on an UNTRUE rumor that 6 Antifa members have been arrested for setting fires" in the area.
“This is not true”, said the post.