Christie appeared to grab the Colombian international in the groin area.
The Scottish FA has issued the Celtic player with a violent conduct charge and he will face a hearing on 6 January.
Christie, who now faces a two-game ban, had been booked for an earlier offence, but escaped punishment for the Morelos incident from referee Kevin Clancy.
The Scotland midfielder reportedly needed emergency groin surgery after being injured in a separate tussle with Morelos in Rangers' 2-1 win.
Christie has been adjudged to have breached Disciplinary Rule 200 which states: "Where any one of the sending off offences of (A1) serious foul play, (A2) violent conduct, and (A3) spitting at an opponent or any other person is committed by a player at a match, but that sending off offence was not seen by any of the match officials at the time that it was committed, the mandatory suspension for that sending off offence as provided for in Annex C of the Judicial Panel Protocol shall be applied to the player."