Talking to reporters here, Chennithala warned that Congress "will not keep silent" if its party offices were attacked.
He alleged that CPI(M) was taking law into their hands by resorting to widespread violence. "People have to evaluate whether it was right on the part of political parties to take law into their hands," he said.
Chennithala said, "I would like to remind CPI(M) that if it was choosing the path of violence, then it will have to pay heavy price for it".
UDF will observe August 9 as 'quit violence' day in Kannur, he said.
Offices of various political parties were attacked in the state in the dawn-to-dusk hartal called by Left parties yesterday to protest arrest of Jayarajan, CPI(M) Kannur district secretary, in connection with the murder of IUML's youth wing activist Abdul Shukkoor at Ariyil in February.