An apparent VAR failure saw Wydad denied an equaliser that was wrongly ruled offside by the linesman.
That effort came just before the hour-mark and although play briefly resumed, there was a long delay prior to the referee seemingly blowing for full-time.
However, the CAF executive committee met in Paris on Thursday (AEST) and ruled "the second leg match must be replayed on another ground outside Tunisian territory".
"The conditions of game and safety were not met during the second leg of the CAF Champions League final held on 1 June (AEST), 2019, preventing the match from coming to an end," part of a CAF statement also read.
ES Tunis has been ordered to return the trophy and medals awarded.
The date and venue of the second leg is yet to be determined, with the tie locked at 1-1 after the opening game in the Moroccan capital, Rabat.