A heartless New York City man was arrested for punching and stabbing a woman at the World Trade Center Memorial, according to cops. 

The incident unfolded around 2 a.m. Friday, when Amir Thompson is accused of approaching the 57-year-old woman in the plaza on the corner of Liberty and West streets in Lower Manhattan.

“I know you from somewhere,” Thompson, 23, allegedly seethed at the victim before punching her, then knifing her in the right cheek and shoulder, according to a police source.

Another cop source said both of the parties threw punches before the blade came out. 

Thompson then flashed the knife at a police officer who responded to the chaos from a booth near the memorial, the sources said. 

“What are you going to do,” Thompson allegedly threatened the officer. 

He ended up dropping the knife, and was arrested, the first source said. 

The victim was taken to New York-Presbyterian Lower Manhattan Hospital in stable condition. She and Thompson — who was living at the Bowery Mission in Tribeca — did not know each other, according to cops.

Thompson was slapped with assault, criminal possession of a weapon and menacing charges. He was expected to be arraigned in Manhattan Criminal Court on Saturday. 

Additional reporting by Georgett Roberts.