Bloomberg also said that "we have no idea who did this and why".
Bomb-squad staff were deployed in the busy square in the heart of Manhattan late on Saturday and police shut down several streets after a T-shirt vendor, who saw smoke emerging from the car, alerted police.
There were reports of a small flash and popping sounds also coming from the car.
Nearby life normal
Al Jazeera's Kristen Saloomey, reporting from Manhattan, said that while Times Square was shut down, life was going on as usual in areas nearby.
"New Yorkers have lived through many scares," she said.
"The [four-wheel vehicle] was a Nissan Pathfinder with licence plates from the state of Connecticut.
"The plates were actually traced and found to belong to another vehicle so obviously investigation is still going on."
The purpose of the bomb was to create "a significant amount of fire," Raymond Kelly, the city police commissioner, said.
He said that after an examination by bomb squad experts, the vehicle will be moved to a police location.
"The vehicle will be examined for DNA and fingerprint evidence."
The square was reopened after car had been removed.
Bloomberg said that "terrorists around the world", who want to take "freedoms" away from the Americans, always focus on the symbol of those freedoms - New York City.
Riad Kahwaji, a security analyst from the Institute for Near East and Gulf Military Analysis in Dubai, said it was "premature" to accuse international terrorists.
"We shouldn't jump into conclusions here," he told Al Jazeera.
"We have a precedent here, back in the 1990s, of the attack on the FBI building in Oklahoma city. People immediately accused Islamic militants and it turned out [the culprit] was one of the right-wing fundamentalists from inside the US.
|Two alarm clocks were attached to the device found in Times Square [Reuters]
"Right now, the big bogeyman is al-Qaeda, the Islamic terrorists. ... For the US, it's always safe and good for their own political advantage to accuse the Islamic militants even if it turned out that they have nothing to do with it."
Phil Rees, the author of Dining with Terrorists, dismissed Bloomberg's comments about terrorists targeting American freedoms.
"I've spoken to Islamists for 20 years. They don't give a jot about my life style in the United Kingdom or what goes on in America," he told Al Jazeera.
"They care about American foreign policy, what the United States is doing in Muslim lands, not just in Iraq and Afghanistan, but the way it has corrupted many Muslim leaders, the way that it prevents democracy emerging in Muslim lands, the way that it obviously doesn't look at Palestine and Israel in equal terms."
A statement issued by the White House said the New York police department had done "excellent work" in responding to the incident.
Unconfirmed reports said someone had been seen running from the car.
The vehicle had been parked close to a theatre on the corner of 45th Street and Seventh Avenue showing a production of The Lion King.
Times Square is one of the city's most high-profile attractions and police are deployed there in large numbers.
In December they closed the area while inspecting a van at first feared to contain a bomb, but which turned out to be carrying nothing dangerous.