The Portuguese was highly critical of the official after his side’s Premier League match against Burnley on December 21 where he said: “The referee does not have the quality to whistle a game in the Premier League.”
Santo has been charged with a breach of FA Rule E3.
A statement from The FA said “It is alleged that comments made by the head coach during a post-match interview constitute improper conduct as they were personally offensive to the match official and/or bring the game into disrepute.”
Nuno has until January 5th to respond to the charge.