Rafa Benitez has been fined £60,000 after accepting a Football Association charge over comments he made about referee Andre Marriner.
Marriner was in charge of last month's goalless draw against Crystal Palace at Selhurst Park.
Benitez was asked about comments Wilfried Zaha had made before the game.
The Palace forward had demanded more protection from officials, and Benitez had been concerned that Zaha's comments were an attempt to influence Marriner.
"I have a lot of confidence with Andre Marriner," said United's manager. "He has a lot of experience, even if his record with our players is not that great in terms of red cards.
"He (Zaha) is a good player, no doubt about that, but I think the FA have to deal with his comments. I think Andre Marriner will not have this in the back of his head.”
However, managers are not allowed to discuss officials before games, and Benitez was charged by the FA.