Rivero did not release information about the suspects or where they were held, rompting demonstrations by family members concerned about the men's whereabouts, CNN reported.
The six women were among 14 people victimized by hooded gunmen who broke into a vacation bungalow in the resort town in Guerrero state Feb. 4, police said.
The attackers also stole cell phones, iPads and tennis shoes from the victims, investigators said.
Investigators said they think the victims bought drugs from at least one of the suspects a couple of days before the break-in and that they knew the men, lead investigator Marcos Juarez said last week.
The Spanish tourists, said to be in their 20s and 30s, were under the protection of authorities in Mexico City, CNN said.
A seventh woman, a Mexican, was spared because of her nationality, Guerrero state Attorney General Martha Garzon said last week.
The gunmen's motive was robbery and "to have some fun," Garzon said.
Officials said the suspects don't appear to be part of a gang.