There is no "specific and credible threat" against New York City, despite a newly released Islamic State (IS) video suggesting America's most populous city is a potential target of attacks such as those in Paris, Mayor Bill de Blasio has said.

Police Commissioner William Bratton agreed with the mayor during an evening news conference by both men in Times Square, saying that there was nothing new about the video, which he called "hastily produced".

"There is no credible and specific threat against New York," de Blasio said, encouraging residents to go about their business as normal while remaining watchful. "Stoking fear is the goal of terrorist organisations, but New York City will not be intimidated."

The IS video, which runs for nearly six minutes, includes a scene that appears to show a suicide bomber making preparations and zipping up a leather jacket, according to a description provided by SITE Intelligence Group, a Bethesda, Maryland, organisation that tracks militant groups.

The clip shows a brief glimpse of Times Square, the midtown Manhattan crossroads popular with tourists, and a suicide bomber holding what appears to be a trigger. Most of the footage is scenes of Paris and French President Francois Hollande.

"Footage of New York shown in the Isis video was taken from a video released by the group in April of this year. So while NYC is, and has been, a target for ISIS, today's video does not warrant any kind of panic," SITE director Rita Katz said.

The FBI said through a spokeswoman it was aware of news reports about the video and ongoing terrorist threats to NYC, and would fully investigate.