Reports in Spain have suggested that three Bayern Munich players allegedly stormed into the referee's dressing room and confronted him following their team's elimination from the Champions League at Real Madrid.
Bayern lost 4-2 in extra time at Real Madrid to go out of the Champions League quarterfinals 6-3 on aggregate.
The players were angered by several key decisions made by Hungarian referee Viktor Kassai.
According to reporter Jose Luis Sanchez, of Atresmedia TV programme "El Chiringuito de los Jugones," Robert Lewandowski, Arturo Vidal -- sent off in the 84th minute for a controversial second yellow card -- and Thiago Alcantara entered the official's dressing room and insulted him before police intervened.
Top Madrid newspaper Marca reported that shouting could be heard in the tunnel after the match.
But a UEFA spokesman said the governing body had not so far received any information regarding those reports.
UEFA later told ESPN FC by email: "No disciplinary cases have been opened following Tuesday's UEFA Champions League matches."
Bayern coach Carlo Ancelotti had expressed his frustration after the game. "He [Kassai] made a lot of mistakes and probably he was not good enough."
On the subject of referees, he said: "At this point I think it's absolutely indispensable. A referee cannot decide a knockout game in this way."
Vidal also said Bayern had suffered a "robbery" at the hands of Kassai, claiming the official, not Real Madrid, had been responsible for their elimination.
"It is very tough when they steal a game from you like that -- two goals offside and me wrongly sent off. When two big teams meet like this in the Champions League, such a robbery cannot happen," he said.
Bayern midfielder Thiago Alcantara told Onda Cero radio: "I don't even have words for Vidal's sending off. It was not a yellow card, it was not even a foul.
"At this level, in the Champions League, you cannot see these types of mistakes.
"Everyone talks about the use of video assistant referees, but what you need is competent referees."