Manchester United manager Sir Alex Ferguson and his assistant Carlos Queiroz were found not guilty of improper conduct by the Football Association on Wednesday, the AFP reported.
The pair had been charged in relation to comments made following United's FA Cup defeat to Portsmouth on March 8.
Ferguson had described referee Martin Atkinson as a "disgrace", declaring that his performance "should not be accepted in our game", after he denied United a penalty for Sylvain Distin's block on Cristiano Ronaldo.
Atkinson also sent off United goalkeeper Tomasz Kuszczak for bringing down Milan Baros and Ferguson claimed that the referees' chief, Keith Hackett, was "not doing his job properly" and picked his "favourites" for United's matches.
Queiroz was just as scathing about Atkinson, saying: "I feel sorry that the game has moved to the situation where referees deserve red cards.
"This referee deserves somebody to come to the side of the pitch after five minutes, give him a red card and pull him out of the game."