The 22-year-old had been due to take on Sierra Leone in an Africa Cup of Nations qualifying double header, with the home game set for Friday 11 October and the return taking place next Tuesday.
However, the United winger will now return to Manchester, where the Reds host Brentford in our next Premier League outing.
Amad was capped by the Elephants for the first time in 2021, and has so far made six appearances at international level.
He was recalled to head coach Emerse Fae's group after a 15-month absence in June, as the 2023 African champions beat Zambia and Chad.