Paul Lambert's side won Tuesday's encounter 4-2 but the game was marred by a scuffle near the end of the game after Blades midfielder Stephen Quinn was sent-off.
United have been charged with the same offence while their winger Andy Reid - who opened the scoring at Carrow Road - has been charged with a separate offence of violent conduct.
The clubs have until January 5 to respond while Reid has until 6pm on Friday.
Source: PA
Source: PA