The party General secretary K.C. Venugopal led the protest at Alphuzza in Kerala and was detained by the police for agitating against the CAA.
The party is organising peace marches in various state capitals and asked the party president to lead the march on December 22, the foundation day of the party. The Congress President has directed the state presidents and chief ministers to lead the agitation in their respective states on that day.
Congress President Sonia Gandhi attacked the government for using "brute force to suppress dissent" and said that it stood by the students and protesting citizens.
In a video message, Sonia said, "the Congress expresses deep concern and anguish on the use of force against students and citizens of the country and stands in solidarity with them."
"In a democracy, people have the right to raise their voices against wrong decisions and policies of the government and register their concerns... The BJP government has shown utter disregard for people's voices and chosen to use brute force to suppress dissent," she added.
Sonia condemned the use of violence during protests and expressed solidarity with the peaceful protesters.
"The CAA is discriminatory and the proposed NRC will target the poor and vulnerable sections of the society."
The Congress, which has not been directly involved in the protests so far with only a few leaders participating, has now come at the forefront of the agitation with its party chief expressing her support to the nationwide stir.
At a meeting of the party's core group on Thursday, many leaders, including General Secretary Priyanka Gandhi, had suggested that the party should support the anti-CAA agitation. The ruling BJP, on the other hand, has long been accusing the Congress of instigating the protests.
( With inputs from IANS )