A police statement says the operation took place today with raids in five towns, including the regional capital Barcelona.
Police say the arrests followed an eight-month investigation in coordination with Belgian police that linked several of the arrested to jihadist organizations as well as organized crime activity.
Police said the suspects were Moroccans residents in Catalonia and aged between 21 and 39.
Spanish police have arrested some 200 suspected jihadi activists since Spain raised its national security alert to one step below the maximum in 2015.