The photos were spotted in pro-Islamic State channels on instant messaging app Telegram, according to terror watchdog group Memri.
One shows a man wearing an IS-branded scarf over his face outside the Metropolitan Museum of Art – and right near an New York Police Department (NYPD) security camera. Pedestrians can be seen walking by on the snow-dusted street, New York Post reported.
Another is of someone holding a smartphone with the terror group’s logo on its screen in front of the World Trade Centre. The phone-holder appears to be standing near the corner of Houston Street and the West Side Highway.
The NYPD said it was aware of the images and is investigating, but “at this time there are no credible threats related to New York City”.
The department would not answer questions about whether it was looking at security footage or what else it was doing to establish whether there was a credible threat, the Post said.
Police see these kinds of photos all the time and they often end up being fakes, law enforcement sources said.
The photos come just weeks after an IS-inspired bomber tried to blow himself up at the Port Authority Bus Terminal during rush hour.
Suspect Akayed Ullah told investigators that he was radicalised through online propaganda.