Belhanda broke his toe last month playing for Ligue 1 leaders Nice while Tannane suffered a thigh muscle injury training with the squad in Abu Dhabi last week.
Bouhaddouz, who has won two caps and plays for German second division club St Pauli, comes in as a late replacement, the Morocco Football Federation announced.
Morocco, who won the African championship in 1976, play in Group C at the finals in Gabon, starting against the Democratic Republic of Congo in Oyem on Jan. 16.
Squad:
Goalkeepers: Yassine Bounou (Girona), Yassine El Kharroubi (Lokomotiv Plovdiv), Munir Mohamedi (Numancia)
Defenders: Amine Attouchi (Wydad Casablanca), Mehdi Benatia (Juventus), Fouad Chafik (Dijon), Manuel da Costa (Olympiakos), Nabil Dirar (Monaco), Hamza Mendyl (Lille), Romain Saiss (Wolverhampton Wanderers)
Midfielders: Youssef Ait Bennasser (Nancy), Nordin Amrabat (Watford), Sofiane Boufal (Southampton), Mbark Boussoufa (Al Jazeera), Mehdi Carcela (Grenada), Karim El Ahmadi (Feyenoord Rotterdam), Faycal Fajr (Deportivo Coruna), Mourir Obbadi (Lille)
Forwards: Rachid Alioui (Nimes), Aziz Bouhaddouz (St Pauli), Khalid Boutaib (Racing Strasbourg), Youssef El Arabi (Al Lekhwiya), Youssef Ennesyri (Malaga).
(Reporting by Mark Gleeson; Editing by Clare Fallon)
