A creep attacked and tried to sexually assault a woman in a Lower Manhattan subway station Thursday night, cops said. 

The assailant punched the 43-year-old victim in the face at the base of the stairs approaching the 4 and 5 train platform at the Brooklyn Bridge-City Hall station around 8:50 p.m., police said. 

He then pushed her to the ground and tried to move her skirt in an attempt to sexually assault her, authorities said. 

A good Samaritan intervened and tried to hold the suspect — described as a man in his 30s wearing all black — but he got away, cops said. 

The victim was taken to Bellevue Hospital with minor injuries, police said.