Police believe a woman's viral video about the alleged attack was deliberately shared to stoke hatred.
ADVERTISEMENTAn alleged fatal attack on a Russian teenager in Germany by a group of Ukrainians is "fake," police have said.
Authorities in the state of North Rhine-Westphalia said they had "no information about such a violent assault or a death".
Viral footage had shown a woman crying as she shared a friend's story about an alleged assault on a 16-year-old Russian-speaking boy in the town of Euskirchen.
But German police said on Twitter that the "fake" was deliberately spread to incite anti-Ukraine anger.
"A video is currently being circulated on the internet reporting an assault on a 16-year-old youth in the Euskirchen area," police said.
"The Bonn police, who are responsible for capital crimes in the Euskirchen area, have no information about such a violent assault or even about a death," they added.
"Experts currently assume that this is a deliberate "fake video" intended to incite hatred."
State security officials are investigating the matter and police have asked the public not to spread the video any further.