DMDK district Aricultural wing Joint Secretary P Ganesan was sleeping in his house when the petrol bombs were thrown inside through the window.
Ganesan suffered burn injuries in leg in the resultant fire which also damaged the rope cot, police said adding he had been hospitalised.
A case of attempt to murder had been registered and investigations were on, they said.
Ganesan alleged that he was attacked because he had campaigned against AIADMK.