Williams said that Ellison called him a "a garbage ass disrespectful mother(expletive)," according to Grant Paulsen of WJFK-FM in Washington.
An NFL spokesperson confirmed that the league is looking into the matter.
"I just don't think there's no room for you to have to take that from the team and the refs," Williams said. "I think it's very unprofessional and it sucks. I'm at a loss for words. You never expect that as a player going into a game to have to beef with the refs also."
Paulsen said that "several" of Williams' teammates verified the claim.
"That's exactly what Mr. Umpire said," guard Kory Lichtensteiger said. "He walked in between me and Trent when he said it."