They had set ablaze the log wrapped in a gunny bag dipped in petrol before throwing it inside the premises at 5am.
Some pamphlets were also thrown inside the premises asking the Centre to respect the feelings and sentiments of Tamilians and Prime Minister Manmohan Singh and Khurshid not to attend the Commonwealth Heads of Government Meeting.
The incident comes a day after two petrol bombs were hurled at two post offices in Chennai in the wee hours on Tuesday. Four persons belonging to the Periyar Dravidar Kazhagam were arrested in this connection.
Some political parties in Tamil Nadu have been demanding that India boycott the CHOGM to be held in Sri Lanka next month on the Sri Lankan Tamils issue.