In one of the attacks, he knocked a 23-year-old woman to the ground and touched her genitals before getting away on an electric bike along Central Park West, a block from the Museum of Natural History.
Police say the same man approached a 28-year-old woman from behind near Tompkins Square Park in the East Village.
The man claimed to have a knife and forced the woman to perform a sex act on him.
Both women sustained abrasions in the attacks.
ALSO READ | New York City shares steps people should take in event of nuclear attack
Nuclear attack preparedness highlighted in NYC video
----------
* Get Eyewitness News Delivered
* More Manhattan news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube
Submit a tip or story idea to Eyewitness News
Have a breaking news tip or an idea for a story we should cover? Send it to Eyewitness News using the form below. If attaching a video or photo, terms of use apply.