Vienna - UEFA has warned all the Champions League quarter-final teams to stop their players harassing referees, secretary general Gianni Infantino has said on Monday.
And Europe's governing body does not support extending video technology to catch mistakes made by referees, he added.
UEFA's refereeing officer Pierluigi Collina warned Atletico Madrid, Barcelona, Bayern Munich, Juventus, Monaco, Paris Saint Germain, Porto and Real Madrid at a meeting on Friday.
The meeting at the UEFA headquarters at Nyon in Switzerland came the day after the ruling body banned Paris St-Germain's Ivorian defender Serge Aurier for three European matches for "insulting acts" towards the referee of the Champions League match against Chelsea.
Aurier did not play in the March 11 match which ended in a 2-2 draw, but made disparaging comments on Facebook about referee Bjorn Kuipers over his dismissal of Zlatan Ibrahimovic.
UEFA is concerned about the growing tendency of groups of players to surround referees after every controversial call. Infantino slammed what he called the "aggressive stance" of some players toward referees.
"This is something that we don't accept, that we cannot accept and we are very clear about that," he said.
"We also have to protect the referees and respect the referees," added the UEFA official. "It must be something that lives in the actions of the players.
"We understand that there are tensions around matches," said Infantino. "But the respect for the referee is the basis for playing."
The English Premier League has been rocked by controversy over the mistaken sending-off of West Brom defender Gareth McAuley after just 89 seconds of their 1-0 Premier League defeat at Manchester City. His teammate Matt Dawson committed the foul.
Infantino said more technology was not the answer, although he felt there had to be more debate on the issue.
"There would be no mistaken identity if you had the additional assistant referees, because they will see immediately what happens and can rectify all decisions," he said.
"But, for everything else, it's very much a judgement question for the referee - and has to remain with the referee as well in the future.