Reports suggest that the two players had to be held apart by teammates following last weekend's 2-0 win over Lyon after the pair had clashed over set piece duties.
Forlan has since weighed in on the incident, criticising Neymar as well as PSG's veteran Brazilian Alves for his role in the incident, which allegedly entailed stealing the ball from Cavani.
"[Cavani] knows how to handle himself and knows how to talk in a situation like this," The Sun quotes Forlan as saying.
"Outside he does not have to be friends with anybody, but then inside the field they are a team and they have to get along.
"I get angry if I put myself in the place of Cavani, because Alves, at the moment [Cavani] wants to kick the penalty, was concerned to get the ball [for Neymar], as if they were little boys."
Alves has hit back at Forlan, denying that there was even a bust-up between PSG players during the match and warning the veteran to "stop making controversy".