The Big Apple is a popular destination on December 31, with about one million people packing into Times Square every year for the countdown to midnight.
"I certainly understand that everyone's concerned and I want everyone to understand and to hear that the NYPD is ready, that the preparations for New Year's Eve are more extensive than ever," De Blasio said in a local radio interview.
After the Paris attacks on November 13, an Islamic State group propaganda video broadcast images of New York from Times Square.
Authorities hit back that there was no credible threat against the city or anywhere else in the United States, and have sought to reassure a jittery public.
"This is the best prepared city in this country to stop terrorism, and people should rest assured that they will be very well protected on New Year's Eve," De Blasio said.