The accident happened in the town of Sidi Boulaalam, about 60 kilometres from Essaouira, the interior ministry said in a statement.
Local media said a "benefactor" had organised the food distribution at a stall in the rural town, which was rapidly "submerged in the crowd" of 800 people, mostly women.
An investigation has begun to "determine the circumstances of the incident" and establish who was responsible, the Moroccan authorities said.
The interior ministry said King Mohammed VI had issued orders to "provide the necessary help and support to the families of the victims and the injured".
He also decided to "personally cover the costs of victims' funerals and burials, and the care of the injured," it said.
