Manchester United and Manchester City were asked by the FA for their observations after reports that United boss Jose Mourinho had milk and water thrown at him by City players after the Dec. 10 derby.
"Following a review of the evidence provided by the clubs and independent eyewitnesses, the FA will be taking no formal action," said a spokesperson.
British media reported that Mourinho was upset by City’s excessive celebrations after their 2-1 victory at Old Trafford.
Mikel Arteta, part of City’s coaching team, was also reported to have suffered a cut in the alleged incidents.
Referee Michael Oliver did not witness any post-match incidents and made no reference to anything untoward in his match report.