MLS on Wednesday suspended Miazga for three matches, meaning he will miss Saturday's Eastern Conference final and the MLS Cup final should his team reach the title game.
The sanction came after Cincinnati's playoff game at the New York Red Bulls on November 4. The referee's association had posted a statement on social media saying that a player had entered their locker room after the match, in breach of MLS rules.
The statement said the player had to be "forcibly removed by stadium security while acting in an aggressive and hostile manner."
Multiple media reports had named Miazga as the player but the PRSA's description of the confrontation has been challenged, particularly the issue of whether security had to be used to remove Miazga.
The players union challenged the referees' association version of the incident.
"The MLS Players Association condemns the behavior of the Professional Soccer Referees Association (PSRA) and certain PSRA members with regard to the Nov. 4 incident at Red Bull Arena involving FC Cincinnati player Matt Miazga," the MLSPA said.
The players union said that the referee's body had "created and repeatedly reinforced a false public narrative that appears to have directly influenced that process.
"Video footage made available and reviewed during the disciplinary process confirms that statements made by the referees and the PSRA were false.
"Unfortunately, that evidence does not appear to have been appropriately factored into MLS' decision," the MLSPA added.
The union criticized MLS for not taking action against the referees.
"No discipline has been announced for the referees for submitting a match report with multiple false statements and no discipline has been announced to address the stadium security breakdown that allowed the incident to occur in the first place," the union said.
"Further, MLS has not publicly condemned the PSRA for their irresponsible actions and false statements.
"Players in MLS are held publicly accountable for their actions. It is high time that the same standard be applied to officials.
"The behavior of the referees and the PSRA in this case did not demonstrate a level of integrity commensurate with a league of MLS's stature."
Noonan: ban excessive
FC Cincinnati head coach Pat Noonan said MLS's sanction, which robs him of the league's defensive player of the year, was excessive.
"Matt made a mistake and now we're −- he's paying the consequences," he told reporters after training ahead of Saturday's home MLS semi-final with Ohio rivals Columbus Crew.
"Having said that, I think the punishment is way over the top for the actions that transpired. I think this is something that's unprecedented.
"Taking everything into account, I think this could have been a heavy fine and you try to keep your most important players on the field for key games.
"If you look at the NBA or the NFL, some of these other leagues, are you really taking off your top players in key moments because of things like this? I think you probably don't?"
Noonan said that the referees should address the disputed claims about the incident.
"I also would like to see just some transparency and accountability with the officials. At some point, Matt's going to have the opportunity to talk about it," he said. "Let's have an official up here talking about what transpired."
Miazga, 28, began his career with the Red Bulls before he was sold to Premier League club Chelsea, but spent the bulk of his time on loan at clubs in Europe.
He joined Cincinnati in 2022 and has been a key part of the club's rise this season, which saw Cincinnati earn the playoffs top seed after finishing with the best regular-season record.
Miazga has played 28 times for the US national team.
