Police said the fishermen from Rameswaram were attacked with iron rods and ropes while fishing near Katchatheevu, an islet ceded to Sri Lanka by India in the 1970s.
One of the fishermen, Anthony, who was injured in his fingers, had been admitted to a hospital at Ramanathapuram.
President of the Rameswaram Fishermen's association, Sagayam alleged thatfishermen onboard nearly 50 boats were driven away by the Lankan personnel.