Police launched a manhunt to track down the group after the first explosion last month in a Casablanca internet cafe. The bomber, Abdelfattah Raydi, detonated his explosives after the cafe owner caught him surfing extremist websites.
Authorities say the crackdown derailed a plot to attack Casablanca's port and police stations, and tourist sites around Morocco.
Last week, police acting on a tip flushed four suspects out of a hideout in the Casablanca neighbuorhood of Hay al-Farah, shooting one dead and prompting the other three to blow themselves up. A policeman was killed in the blasts and 21 bystanders injured.
In other attacks on Saturday, bombers blew themselves up outside the US consulate and American language centre in Casablanca's city centre. One passer-by was injured.
Police said they had arrested the unidentified group's leader on the same day and uncovered bomb-making workshops.