Cleveland Browns wide receiver Odell Beckham Jr is subject to an arrest warrant from New Orleans police on a charge of alleged simple battery.
A video appears to show Beckham Jr striking a security guard's backside in Louisiana State University's locker room on Monday after their national championship win over Clemson.
Beckham Jr, 27, is a former LSU player.
New Orleans police said they had obtained an arrest warrant on a charge of misdemeanour simple battery.
The incident occurred at the Mercedes-Benz Superdome in New Orleans.
In a statement on Thursday, the Browns said: "We are aware of the incident and have been in touch with Odell and his representatives on the matter.
"They are cooperating with the proper authorities to appropriately address the situation."
In another video Beckham Jr appears to be handing out money to LSU players after they won college football's most prestigious prize.
That would be in contravention of NCAA rules, which prevent student-athletes from receiving "impermissible benefits" such as cash.
LSU initially said it believed the money to be fake but quarterback Joe Burrow - who will enter the NFL draft next season - said it was real.
In a subsequent statement, LSU said: "Initial information suggested bills that were exchanged were novelty bills.
"Information and footage reviewed since shows apparent cash may have also been given to LSU student-athletes.
"We were in contact with the NCAA and the Southeastern Conference (SEC) immediately upon learning of this situation in which some of our student-athletes may have been placed in a compromising position.
"We are working with our student-athletes, the NCAA and the SEC in order to rectify the situation."
After a three-year college career at LSU, Beckham Jr was drafted by the New York Giants in 2014 before he was traded to the Browns for the 2019 season.
He recorded 1,035 receiving yards and four touchdowns as the Browns failed to reach the play-offs.