The statement, written in Basque and published in the Basque daily Gara, said a police officer had fired two shots towards one of four activists they had already captured before other ETA militants intervened.
President Nicolas Sarkozy vowed to wipe out ETA bases in France after 52-year-old Jean-Serge Nerin became the first French police officer to be killed by the separatists following the March 16 gun battle.
The ETA statement said French officers had captured the four ETA activists in a forest near the town of Dammarie-les-Lys, 50 kilometres (30 miles) southeast of Paris after they had stolen several cars from a local dealership.
They had given a clear warning to the French police officers, telling them throw down their weapons and leave: in the subsequent gun battle, ETA militants had fired nine shots, the French police many more, the statement said.
ETA, banned as a terrorist group by the European Union and the United States, is blamed for 828 deaths in its 41-year campaign for independence for the Basque region of northern Spain and southwestern France.