Video: Brian Mujati pushes Nigel Owens
Mujati was cited after the incident and the independent judicial officer, Rod McKenzie, ruled on Monday that the player had been guilty of an act contrary to good sportsmanship.
McKenzie however determined the offence was low-end in terms of its seriousness and accepted there were "compelling and exceptional mitigating factors" in that Mujati was suffering from concussion at the time of the incident.
Barring a successful appeal, Mujati will not be allowed to play until December 2, meaning he will miss four matches for Northampton.