Some BJP workers were injured in the attack and treated as outpatients at a hospital, they said.
Cases had been registered against the group of persons who resorted to violence and attacked Muruganandham when he was campaigning in the Mallipattinam area, police said.
MDMK leader Vaiko strongly condemned the "indiscriminate" attack on the BJP cadres.
In a statement here, he said some violent group had asked the BJP men and cadres not to enter the Mallipattinam area. Though BJP workers explained that they had democratic right to seek the vote from the people in the area, the violent crowd stopped and threatened them before attacking them with country weapons, he charged.
Police had initially refused to register the complaint but relented only after the BJP workers staged a "non-violent" protest.