By Tania Lopez and Candice Ruud

NYPD Commissioner William Bratton and Mayor Bill de Blasio had a message for New Yorkers in an unusual late-night news conference in Times Square last night: Keep going about your business.

Bratton and de Blasio addressed a new ISIS propaganda video in which images of Times Square were shown, and both men underscored the assessment that there is no "specific, credible threat" against New York City.

"We cannot be intimidated, and that's what terrorists seek to do," Bratton said as he addressed reporters and a crowd that gathered about 11 p.m. "They seek to create fear, they seek to intimidate, and we will not be intimidated and we will not live in fear."

John Miller, assistant NYPD commissioner, acknowledged earlier on CNN that the department has been stepping up its anti-terrorism activity in response to heightened tension after the Paris attacks.

"We're getting more calls. We're going on more runs . . . that's what we do," he said.

At the news conference, de Blasio called the video "an obvious attempt to intimidate New York City . . . the people of New York City will not be intimidated."

"We will not submit to their wishes," de Blasio said. "I want to encourage all New Yorkers to go about their business normally."

He added that this week, the city initiated the first wave of its Critical Response Command, 500 officers trained to handle terrorist threats.

De Blasio urged New Yorkers to be vigilant, reminding them of the motto: "If you see something, say something."

Bratton, speaking after the mayor, said there is "no city in America that is better prepared" to deal with a terrorist attack.

"There is nothing new about that video," he said of the ISIS video, which he called a "mishmash" of old video clips. And, he encouraged New Yorkers and tourists to come into the city to celebrate the holidays.

"Be aware but do not be afraid," Bratton said. "The NYPD will protect you."

The video, purported to be the work of the Islamic State group, is about 5 1/2 minutes long, and intersperses images of men holding semi-automatic weapons and strapping on suicide bombs with shots of Times Square and footage of French President Francois Hollande at his inauguration and after the Paris attacks that killed 129 and injured hundreds.

Militants dressed in black and speaking to the camera in French are also featured in the video, which like other Islamic State videos was set to music and appeared professionally produced. The ISIS video also shows a suicide bomber preparing for an attack in a crowded Times Square, showing many yellow cabs and the TGIFriday's restaurant. When he pulls the trigger, the screen cuts to black.

Words promising, "What is to come will be worse and more bitter," then appear in both French and Arabic script.

"I want every New Yorker to know that their security is our absolute highest priority," Gov. Andrew M. Cuomo said in a statement Wednesday night. "After the Paris attacks, I directed state agencies to enhance their preparedness out of an abundance of caution. . . . and remain in close contact with local and federal authorities, including the FBI and NYPD through the Joint Terrorism Task Force, and that vigilance continues today. I encourage all New Yorkers to remain alert and report any suspicious activity, while at the same time not letting this disrupt their daily lives. Remember that the terrorists' goal is to let fear win -- New Yorkers never have, and we never will."

With Alison Fox, Emily Ngo and Michael Gormley

(c)2015 Newsday