Joe Marler has been reprimanded after a scuffle with England team-mate James Haskell during Harlequins' Premiership victory over Wasps on Sunday.
Wasps flanker Haskell, who was sin-binned, said he retaliated because Quins' Marler choked him with his scrum cap and squirted water at him.
Prop Marler, who was not punished at the time, has been given a citing commissioner's warning, which equates to a retrospective yellow card.
Harlequins won the match 24-21.
If a player accumulates three yellow cards in one season they will either be banned for one game or face a disciplinary hearing.