"The appeal lodged by Paris Saint-Germain is rejected. Consequently, the UEFA Control, Ethics, and Disciplinary Body’s decision of 25 April is confirmed," UEFA announced in a statement.
"The CEDB had decided to suspend the Paris Saint-Germain player Neymar Junior for three UEFA competition matches for which he would be otherwise eligible for insulting match officials."
Neymar will miss half of PSG's Champions League group stage matches next season as a result of his comments following the French club's elimination by Manchester United in the round of 16 earlier this year.
The 27-year-old's outrage was sparked after a controversial VAR decision awarded United a decisive stoppage-time penalty. Neymar, who didn't feature in either leg due to an injured right foot, blasted officials on social media, labeling the decision a "disgrace" while directly insulting the officiating staff.
Neymar was also suspended for an additional three domestic matches in May after he struck a supporter in the face following PSG's shock defeat in the Coupe de France final. He sat out PSG's final two league matches and will miss their French Champions Trophy encounter with Rennes in August.