The video purports to show an explosive device being put together and a bomber zipping his jacket over a suicide belt.
The New York City Police Department said it was aware of the video and was deploying additional members of its new anti-terrorism squad out of an abundance of caution, CNN reported.
"While some of the video footage is not new, the video reaffirms the message that New York City remains a top terrorist target," the statement said. "While there is no current or specific threat to the city at this time, we will remain at a heightened state of vigilance and will continue to work with the FBI, the Joint Terrorism Task Force and the entire intelligence community to keep the city of New York safe."
The video prompted a response from Mayor Bill de Blasio, who said police were "taking all necessary precautions" in areas shown in the video and throughout the city.
"Stoking fear is the goal of terrorist organizations, but New York City will not be intimidated," he said.
A similar video was released in April, according to John Miller, the NYPD deputy commissioner of intelligence and counterterrorism.
"This is an old video that was kind of rehashed," he said. "This is ISIL doing what ISIL and al Qaeda and terrorist groups do, which is propaganda."
"When we see the video, we make note of it, but it's like a lot of videos we've seen," Miller said.
Terrorism analyst Paul Cruickshank said authorities can't ignore the video, whether or not it turns out to be a credible threat.
"I think they have to treat it quite seriously, because ISIL is the richest terrorist group in history. It has an extraordinary number of Western recruits. ... One of its biggest ambitions right now is to a launch a terrorist attack inside the United States," he said.
ISIL first drew international attention for taking over swaths of Iraq and Syria, leaving a trail of violence and destruction in its wake. Its efforts to bring terror to the global stage seem to be growing. This month alone, ISIL has claimed responsibility for the Paris attacks, the downing of a Russian passenger jet in Egypt and a pair of suicide bombings in Beirut.
Earlier this week, another video released by ISIL threatened to strike Washington.
Authorities in the US capital said they were stepping up security. The FBI said there was "no specific or credible threat to the United States."