Karunandhi said in a statement: "At a time when Muslims are being attacked, the central and state governments should come forward with their views to protect them."
He said the US had condemned the attacks on Muslims in some parts of Sri Lanka. Other countries too had denounced the attacks.
At least three people were killed and over 100 injured when Buddhist radicals unleashed violence against Muslims in Sri Lanka, attacking homes and businesses besides mosques.
Muslims in Sri Lanka, who speak both Tamil and Sinhala, are the second largest minority after Tamils in the Sinhalese-majority island nation.