According to TMZ, a male party-goer filed a police report claiming his girlfriend was making out with Paris on the dancefloor when a jealous River punched him.
The man allegedly needed medical attention after the fight.
River, 21, was arrested for misdemeanor battery. He was cited and released without ever going to the police station.
Hilton, 31, had already left the scene by the time cops arrived but she has not been accused of any wrong doing.
Her representative was unavailable for any comment on the issue.
