National police chief Badrodin Haiti said 12 suspects had been detained in nationwide raids since Thursday's attacks, including one accused of bankrolling the suicide bombings and shootings that left seven dead.
"One of the people detained had received financial transfers from ISIS to fund the operation," he told reporters, using another acronym for IS.
The attack has been claimed by IS, which has ruthlessly carved out a self-proclaimed caliphate in Syria and Iraq, and Indonesian police have more specifically blamed a Southeast Asian affiliate of the group known as Katibah Nusantara.