Players from both sides clashed after the final whistle of the 0-0 draw at Stade du Hainaut, with Prior seen recoiling after a coming-together with Sochaux's Ousseynou Thioune.
"Jerome has a bite on his cheek," said Valenciennes head coach Olivier Guegan after the match. "I was in the dressing room; I didn't see anything.
"It's a shame the post-match will tarnish the game, but that's not the most important thing. We put in a coherent and strong performance against a team that is unbeaten and in a really good dynamic. I really liked the spirit of the group."
Prior was quoted by So Foot as saying: "There are pictures. The league and justice will do their job. I have no comment to make."
Sochaux coach Omar Daf suggested his players had been provoked, saying: "A player doesn't go crazy without something happening first.
"I heard insults at the end of the match. There was a lot of provocation, but you have to have more control."
Sochaux is third in the table, three points behind leader Paris, while Valenciennes is eighth.