Referee Michael Oliver was surrounded by several United players after midfielder Ander Herrera was sent off for a second yellow card 10 minutes before halftime after two ill-judged tackles on Chelsea forward Eden Hazard at Stamford Bridge.
United admitted the charge and received the standard fine.
“It (the charge) relates to a breach of FA Rule E20(a) for failing to ensure its players conducted themselves in an orderly fashion in or around the 35th minute of their FA Cup quarter-final against Chelsea on Monday 13 March 2017,” the FA said.
United manager Jose Mourinho, back at the club where he won seven major trophies, and Chelsea coach Antonio Conte had to be separated after an angry exchange shortly after the sending off.
Chelsea won 1-0 with a 51st minute goal from N’Golo Kante.