FA charge Babel over Twitter joke
The FA said in a statement that the Dutch forward had until January 13 to respond.
"The charge relates to comments and images published by the player on Twitter concerning referee Howard Webb," the ruling body added.
Webb, who officiated at last year's World Cup final between Spain and the Netherlands, awarded United a penalty in the opening minute of their FA Cup third-round match at Old Trafford on Sunday.
After the 1-0 defeat, Babel posted a mocked-up picture of Webb in a Manchester United shirt, adding: "And they call him one of the best referees? That's a joke."
The player later apologised.