According to police, a 50-member group, suspected to be members of 'Hindu Jagaran Vedike', raided the home-stay at Padieelu alleging that a rave party was being held there and assaulted girls and boys injuring them.
The faces of some girls were also blackened, police said.
Police rushed to the scene and arrested more than 20 people, including a city corporation councillor.
Chief Minister Jagadish Shettar, meanwhile, directed Home Minister R Ashoka to get a report about the attack.
"I have asked the Home Minister to get details (about the attack) and a give a report about the incident. Then we will take action," Shettar told reporters in Bangalore.
The return of moral policing in Mangalore, a coastal region, which witnessed similar incidents three years ago, has triggered a wave of condemnation from opposition parties and women organisations against the BJP government.
Hundreds of locals, including women, staged protests alleging that police have not taken steps to check illegal activities in the home-stay despite complaining on several occasions.
However, Deputy Commissioner of the district Chennappa rejected the charge and said "it is a private building where paying guest facilities were being offered. There was no complaint from anyone to the district administration."
While state unit Hindu Jagaran Vedike President Jagadish Karanth defended the attack and demanded a check on such "obscene activities", Congress leader V S Ugrappa lashed out at the government for its "failure" to maintain law and order and ensure communal harmony.
State Women Commission Chairperson Manula decried the attack and wanted the government to punish the culprits.
Three years ago right wing organisation 'Sriram Sene' activists had raided pubs in Mangalore, which had hit the headlines then.
