The incident, which left the victim needing stitches, took place at Kununurra’s Swim Beach, the Kimberley Parks and Wildlife Service has reported.
Rangers are now looking to remove the crocodile from the area.
Freshwater crocodiles, which are smaller and more timid than saltwater crocodiles, are not ordinarily considered to be a threat to humans.
However, they can be dangerous when disturbed, Parks and Wildlife warned.
People visiting crocodile habitats are urged to remain croc-wise and avoid encounters to the best of their ability.