ESPN football writer Adam Schefter wrote on his Twitter account that Williams was "Tasered" in the back and hit in the head with a champagne bottle during the brawl, which happened early Friday at a Honolulu nightclub, police say.
Williams was in Honolulu to participate in Sunday's Pro Bowl.
The NFL announced Friday Williams wouldn't play in the game and had been replaced by Minnesota Vikings rookie left tackle Matt Kalil.
Schefter reported Williams has passed a pair of concussion tests since the incident.
Honolulu Police said three men were hurt during the fracas, with two -- including Williams -- requiring brief hospitalization. A fourth man was arrested on suspicion of third-degree assault and authorities indicated additional arrests were likely.