"At no stage was there any risk to the public," he said.
The boys were eventually talked down and brought off the roof using a fire ladder at about 1.30am on Saturday.
The Ministry of Social Development is now investigating.
NZ First youth affairs spokesman Darroch Ball said the incident was just the latest in a series at the facility and operators had ignored government warnings about understaffing.
"We understand there are only 10 (staff), well below the minimum 15 required," he said.
"Assaults on staff, escape attempts and mini riots have gone on here for the past few years," he said.
Mr Ball said immediate intervention and further oversight by the minister of social development was needed.
Further comment has been requested from the ministry.
-AAP