I guess your talking about Off Plan here? If so, since 2003 the legal form of purchase for these types of properties in Morocco has been a contact called VEFA (short for Vente en I’Etat Futur d’Achevement). This is designed to give you complete security and is enforceable in court of law.
In some cases, you might find that a VEFA contract is not offered, so make sure you look at the level of guarantees available. If a contract doesn’t have any guarantees, it does not mean that you should avoid purchasing, but just be aware of the additional risks involved.
In any case make sure you have an external lawyer who clearly understands the purchase process and can talk you though the pitfalls. Good luck.