Their inflatable boat sank near the coastal town of Akhfennir in Tarfaya province as it tried to reach Spain’s Canary Islands, the officials said.
Another 18 migrants, most of them African, survived and were detained for questioning, they added.
Morocco is a key transit point on routes taken by migrants seeking better lives in Europe.
Last month, at least 23 people died trying to climb border fences into the Spanish enclave of Melilla, on Morocco’s Mediterranean coast.
Rights groups say at least 37 migrants died, a toll higher than the official figure.
It was the worst recorded death toll in years of attempts by migrants to enter Ceuta and Melilla, the two main land borders between Africa and the European Union.
Migrant charity Caminando Fronteras says almost 1,000 migrants died or were reported missing at sea in the first half of the year as they tried to reach Spain.