"It was a disorganised cell… I still believe that domestic crime is a more concerning issue than the question of terrorism," Moraes told media on Thursday, as quoted by The Financial Times, adding that the "chance of a terrorist attack during the Olympics in Brazil is minimal."
According to the justice minister, Brazilian police are looking for two more suspects.
The arrested individuals were all Brazilian and took part in an online IS initiation ceremony, Moraes said. They also tried to purchase firearms. All of the arrested will be held in custody for at least two months.
Brazil is set to become the first South American nation to host the Olympics, which will be held in Rio de Janeiro on August 5-21.