The incident occurred between Toulouse’s Norman and Warrington Wolves’ Oliver Holmes during the two teams’ match last Thursday.
The 31-year-old Norman, who spent 11 years playing in Australia’s National Rugby League before joining Toulouse in April, pled not guilty to the offense.
But tribunal chair Justice Sarah Wright and the two side members, both former players, were “entirely satisfied” the act was intentional.
Holmes complained about the incident during the match and also provided a statement to the tribunal.
“The footage of the incident shows a deliberate movement of Corey Norman’s left arm and hand over the top of Oliver Holmes and on to his buttocks,” the ruling said.
“At no point does the footage show a grabbing of the shorts to push Oliver Holmes down as described by Corey Norman.”
Norman initially announced his retirement from rugby league at the end of last year before returning to the sport with Toulouse on a contract running until the end of the current season.
The French side is currently bottom of the Super League with four games left to play this season.