They forced young men marry their beloved when couples were spotted together in public places in Hyderabad and other parts of the state.
At other places, Bajrang Dal, VHP and other saffron outfits held rallies condemning celebration of Valentine's Day.
These organisations had already announced that they would "counsel" boys and girls, if they are minors, and not hesitate to perform "marriages" if couples are majors.
Meanwhile, the authorities in Hyderabad today kept major parks here like Krishna Kant Park and others closed as a "precautionary measure".
The city police warned that they would take action against those who try to take law into their hands.
Meanwhile, parents of a girl held demonstrations at Kushaiguda police station alleging that the members of the right-wing Hindu organisation conducted the marriage of their daughter, who, they claimed is a minor.
They further alleged that the girl is a cousin to one Raju, a painter with whom her marriage was solemnised by the activists.
They had already lodged a complaint with Banjara Hill police station last night after the girl went missing, they said adding that that the activist who spotted Raju with the girl today had performed their marriage.