Jose Mourinho charged his assistant Rui Faria with expressing Manchester United's frustration after the Portuguese manager was sent to the stands in Sunday's 1-1 draw with West Ham.
Mourinho was dismissed for a second time this season, after kicking a water bottle as an angry reaction to a booking for Paul Pogba during the Premier League clash at Old Trafford.
Just last month Mourinho was sent to the stands for disputing a decision in a draw against Burnley and received a touchline ban.
He has also been involved in a rancorous exchange with Chelsea manager Antonio Conte and been fined for comments about referee Anthony Taylor during a frustrating start to the campaign.
The latest result was United's fourth successive home draw in the league - a sequence they have not endured since 1980 - while their points return from 13 games, 20, is their worst since 1989-90.
Mourinho's latest outburst came after Pogba was deemed to have dived to win a free-kick following a challenge from Mark Noble.
Faria said: "The referee explained it to Jose and there is nothing more to say. I think there was frustration from Jose after the yellow card for Pogba. It should be a foul for us but the referee understood it in another way.
"I think everyone saw it but it is part of the game. It was the referee's decision."
Mourinho now faces further disciplinary action, with the Football Association bound to act after it receives referee Jon Moss' report.
Mourinho's dismissal midway through the first half actually came during a good spell for United. They had cancelled out Diafra Sakho's early opener through Zlatan Ibrahimovic and further troubled the West Ham defence.
Marcus Rashford and Jesse Lingard also went close before the break but, in what became a recurring theme, they were denied by goalkeeper Darren Randolph.
Faria said: "We were the best team on the pitch. Defensively we were very compact and offensively we created the chances to win.
"We are showing that as a team we are a strong side and we can do very good things. We created chances that in a normal way should be goals and the game should be won in a comfortable way. It is not happening. We get frustrated."
West Ham took the lead through Sakho after just 90 seconds but were indebted to a brilliant display from Randolph for keeping them in the game after Ibrahimovic's leveller.
Manager Slaven Bilic said: "I am very pleased with the performance for the point.
"The only thing I didn't like, and I said it at half-time, is when you score a goal you should be more confident than before you score. That is kind of natural but the mentality is you are afraid after you score at Old Trafford.
"From our goal to their equaliser we lost 11 or 12 balls unnecessarily when we could exploit that. So in the first half they were better than us.
"They didn't create a lot but they created one and after they scored.
"At half-time we told the players and the way we played second half was really good, if not great, so I have to praise the players. They showed commitment, team spirit, character and most of all character."
Asked about the Mourinho incident, Bilic said: "I don't know if he deserved to be sent off, I don't know the rules.
"It is hard to judge from our angle if it is a dive or a foul so I can understand it but I didn't want him to be sent off."