A passing tugboat came to the rescue of a woman who jumped into the East River on Friday, cops said.

The unidentified woman, who cops said was in her 30s, leaped into the water close to East 34th Street and the FDR Drive around 8 a.m., cops said.

Witnesses told cops that they saw the woman moving back and forth in the water and called out to her, but she didn’t answer, police said.

Workers on a nearby tugboat pulled her in and brought her to shore, authorities said.

She was unharmed and taken to Bellevue for evaluation, according to police.