The Brazil international was incensed that a last minute penalty was awarded to United writing using the Video Assistant Referee (VAR) system.
Referee Damir Skomina controversially adjudged that PSG defender Presnel Kimpembe had handled a shot from United’s Diogo Dalot in the closing stages of the last 16 Champions League tie.
Marcus Rashford scored the resulting penalty, sending PSG crashing out of the competition.
Neymar missed the the match through injury but was in attendance at the Parc des Princes and incensed by what he saw.
“This is a disgrace, they put four people who know nothing about football in charge of looking at the replay for VAR,” Neymar wrote.
“It’s just not possible!!! How is a guy going to hold his hand behind his back” he asked, referring to how Kimpembe jumped as he tried to block Dalot’s shot. “Go f**k yourselves.”
Neymar, the world’s most expensive footballer, has only just returned to the PSG lineup after a lengthy spell on the sidelines due to a metatarsal injury.
PSG will enter the Champions League at the group stages in September after securing a second consecutive French title last weekend.
Montenegro punished for racist chanting
England won the match 5-1 but the victory was soured by racist chants reportedly aimed at a number of players from the crowd.
Monkey noises also appeared to be directed at defender Danny Rose in the games closing stages.
Montenegro’s next scheduled home fixture is against Kosovo on June 7.