"Tamils are being killed since they refuse to bow to the ideology of the RSS. The feelings of the Tamil people can never be trampled by the bullets of the RSS and Modi. We are with you Tamil brothers and sisters #SterliteProtest," he said in a tweet in Tamil.
Violence continued for the second day in Tuticorin on Wednesday and a man was killed in police firing.
On Tuesday, 11 people were killed in a police action on agitators after months-long protests for the closure of Vedanta's Sterlite Copper unit in the port city over pollution concerns turned violent.
ALSO READ: Why are people protesting against Vedanta's Sterlite unit
Condemning the police action, Rahul had in a tweet on Tuesday said that the gunning down of people is a "brutal example of state-sponsored terrorism".
"These citizens were murdered for protesting against injustice," he wrote.
Over 5000 protesters had gathered on Tuesday gathered at a locality to demand the permanent closure of the copper smelter, which has been opposed by locals for polluting their environment.