Midfielder Belhanda, a leading figure as Montpellier won their first French league title in May, has an ankle injury.
Houcine Kharjah of Italian club Fiorentina, who captained Morocco's senior side at the African Nations Cup finals this year, was one of two over-age players included in the under-23 squad by coach Pim Verbeek.
The other was forward Nordine Amrabat, the Royal Moroccan Football Federation said. A maximum of three over-age players are allowed in the squad but Verbeek declined to pick another.
Defender Abdelhamid El Kaoutari from Montpellier and German-born goalkeeper Mohamed Amsif also competed at January's Nations Cup, where Morocco were disappointingly eliminated in the first round.
Morocco's under-23 side will prepare in the Netherlands from next week for the tournament.
Goalkeepers: Mohamed Amsif (FC Augsburg), Yassine Bounou (Atletico Madrid)
Defenders: Mohamed Aberhoune (MA Tetouan), Zakarya Bergdich (Racing Lens), Abdelhamid El Kaoutari (Montpellier), Zouhair Feddal (Espanyol), Yacine Jebbour (Stade Rennes), Abdelatif Noussair (FUS Rabat)
Midfielders: Abdelaziz Barrada (Getafe), Omar El Kaddouri (Brescia), Driss Fettouhi (Istres), Rayane Frikech (Angers), Houcine Kharja (Fiorentina), Imad Najah (PSV Eindhoven)
Forwards: Nordine Amrabat (Kayerispor), Soufiane Bidaoui (Lierse), Soufian El Hassnaoui (De Graafschap), Zakarya Labyad (Sporting Lisbon)