The suspects approached a 26-year-old woman and stole her cell phone at 15th Street and the FDR Drive in the first incident on July 15.
At the same location on July 17, the men approached a 26-year-old man and bashed him in the head with an unidentified object before taking his phone, the NYPD said.
The suspects brandished a gun while robbing an 18-year-old man of his phone on July 27 at 20th Street and Avenue C, police said.
One of the suspects is described as a male between the ages of 20 and 25, standing about 5-foot-8, between 160 and 200 pounds, with a medium complexion and black hair, police said.
The second man is described as between 18 and 24 years old, standing between 5-foot-10 and 6-feet tall, and weighing between 160 and 185 pounds, with a medium complexion and black hair.
The first two robberies occurred about 10:30 p.m. while the third took place about 1:30 a.m., police added.
Anyone with information can call NYPD Crime Stoppers at 1-800-577-TIPS (8477). The public can also submit tips by logging on to the Crime Stoppers website at http://www.NYPDCRIMESTOPPERS.com or by texting tips to 274637 (CRIMES), then entering TIP577.
All calls will be kept strictly confidential.