A 2-year-old girl plunged into the East River at the South Street Seaport yesterday — but was saved by her father and a mystery Frenchman who jumped in after her.

The girl, whose name wasn’t revealed, was walking with her dad and another child up the ramp to the Peking ship when she fell 15 feet into the river at 4:45 p.m.

Her California-tourist father and the Frenchman jumped in after her. The two quickly grabbed the child and brought her to safety.

The father and child were taken by ambulance to Bellevue Hospital at 5 p.m., and the girl was listed in “good shape considering” the fall, said a police source.

The Frenchman hopped in a cab and left.