Greater Manchester Police are looking into the incident which saw Wigan prop Ben Flower dismissed two minutes into Saturday's Super League Grand Final.
Flower knocked St Helens scrum half back Lance Hohaia unconscious with a punch while he was lying on the floor at Old Trafford.
Police say they haven't received any public complaints about the incident, but will continue to work with all relevant people involved.
After the match, Flower said: “I accept I’ll have to live with this for the rest of my career.
"It was a big night and I know I’ve taken the attention away from what was a special event.”
In Flowers absence, Wigan lost the match 14-6.