Walid Atrash of the Israel Antiquities Authority described the find as a "rare discovery."
"The statue, which probably stood in a niche, was part of the decoration of a bathhouse pool that was exposed during the course of excavations. It is made of smooth white marble and is of excellent artistic quality," Atrash said in a statement released by the authority.
"Hercules is depicted in three dimensions, as a naked figure standing on a base. His bulging muscles stand out prominently, he is leaning on a club to his left, on the upper part of which hangs the skin of the Nemean lion, which according to Greek mythology Hercules slew as the first of his 12 labors."
The excavations are taking place at Horvat Tarbenet, the site of a Jewish settlement in the third century, the authority said. Archaeologists also uncovered dwellings and a well.
At the beginning of the last century, the Jezreel Valley Railway passed through the area as it linked Haifa and Damascus. The antiquities authority said it is working with the Israel National Roads Co., which is rerouting and renewing the old railway line along a 37.2-mile route that will eventually run from Haifa to Afula and Beit She'an.