PSG coach Thomas Tuchel has warned Neymar to show more respect after the forward was involved in an altercation with a spectator following Saturday's Coupe de France final defeat to Rennes, with video footage appearing to show him striking the fan.
Rennes stunned PSG 6-5 on penalties after coming from two down to draw 2-2 in a match in which Neymar got on the scoresheet.
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Ninguém gosta de perder, eu então ... quem me conhece sabe o quanto sou competitivo e o quanto a derrota me abala. Mas perder faz parte da vida de um atleta, nos faz crescer, nos faz pensar, nos faz MELHORAR. Feliz de poder voltar a jogar, de voltar a fazer gol e me sentir bem dentro de campo, mas o sentimento maior hoje é de tristeza. 🙏🏽
As the PSG squad walked up to receive their runners-up medals, Neymar initially pushed a supporter's hand away as he tried to record him on his mobile phone.
The frustrated forward, who returned from a three-month injury layoff last week, then appeared to jab at the spectator before walking away to collect his medal.
Speaking with the press on Monday ahead of Tuesday's Ligue 1 trip to Montpellier, Tuchel recognised that Neymar was out of line.
"I do not like it," the German told journalists. "You cannot do that. It is simply not possible to do it. I have not seen it, but everybody told me about it. I was also there.
"It was not easy going up to collect the medals after the defeat -- it was difficult for me, as well as everybody else. However, we have to accept it. If we win, it is easier. In defeat, you must show respect -- always.
"You simply cannot get into conflict with a spectator."
The former Barcelona and Santos man could face a maximum suspension of eight games if a disciplinary committee deems his actions are worthy of further investigation.
Neymar, who criticised the attitudes of some of PSG's young players after the match, later posted a message on Instagram, saying: "Nobody likes to lose. Everyone who knows me knows how competitive I am and how much defeat shakes me.
"But losing is part of an athlete's life, it makes us grow, makes us think, makes us better. Happy to be able to play again, to score again and feel good on the pitch, but the biggest feeling today is one of sadness."
Tuchel did not want to go into detail over Neymar's criticism of some of his younger teammates after the Coupe de France final, but as well as insisting that there is no problem between the Brazilian and Mbappe, Tuchel also hinted that he shares Neymar's point of view -- to an extent.
"The only thing that I can say is that there are players who like to win, and others who hate to lose," he said.
"We need more players who hate losing, and are used to showing that day in and day out."
Earlier this week, Neymar was suspended for three Champions League games for insulting match officials following PSG's elimination from the Champions League.
PSG have qualified for next season's tournament by winning the Ligue 1 title.
ESPN FC PSG correspondent Jonathan Johnson contributed to this report.