The UN and AU called for an investigation into the deaths of 23 people, after hundreds of migrants tried to enter the Spanish enclave of Melilla from Morocco.
According to Moroccan authorities, a number of people were crushed to death in a stampede on Friday after a section of border fence was cut open, while others may have been killed after falling from a border fence.
Spanish Prime Minister Pedro Sánchez has blamed people traffickers.
AU commission chairperson Moussa Faki Mahamat expressed deep shock and called for an immediate investigation into the matter.