The incident happened during the first half of the Liverpool - Arsenal game. Mane reportedly was elbowed in the face by Swiss international. After that, the Liverpool winger put his hands around the neck of the Swiss for a second or two.
Referee Michael Oliver saw the incident, stopped the game and awarded a free-kick, so most probably Mane will not face any retrospective punishment as it already was in the form of a free-kick.
The Senegalese is allowed to play against Man City on January 3.