It came after they had been turned down for an employment program.
Young Muslims have been demonstrating against unemployment in the Spanish North African enclave of Melilla.
One policeman was hit by a thrown stone as the youths set up barricades in the streets, and set fire to cars and rubbish containers after they had been told they had not been selected for an employment plan.
The disturbances lasted for some five hours in the Muslim districts of the city, and forced the police to use anti-riot gear. Official figures from the Government say there were 50 demonstrators, but other reports speak of 100 or so, most of them under age.