Protesters vowed a new round of demonstrations in New York on Thursday after a grand jury decided not to charge a white police officer in the chokehold death of an unarmed black man on Staten Island.

The grand jury cleared New York Police Officer Daniel Pantaleo in the death of Eric Garnerduring an arrest attempt in July. The decision was announced just over a week after a Missouri grand jury declined to charge a white policeman who shot and killed unarmed black teenager Michael Brown in the St. Louis suburb of Ferguson, touching off rioting, looting and burning in protest.

Hundreds of protesters swarmed the streets in midtown Manhattan on Wednesday night, many chanting "I can't breathe," the same phrase Garner repeatedly gasped in a video of the incident on a Staten Island sidewalk before his death. Police reported 83 arrests by Thursday morning.

People demonstrated in other cities, including Oakland, Washington, D.C., and Denver, where about 100 demonstrators blocked traffic overnight.

De Blasio, who took office in January promising to repair relations between minority New Yorkers and the police department, was expected to address the media at 1:30 p.m.

The PBA's Lynch delivered a forceful defense of Pantaleo's actions, saying he properly applied a technique he had learned in training.

"He's a model of what we want a police officer to be," Lynch said.

Earlier on Thursday, Garner's wife, Esaw Garner, rejected the condolences offered by Pantaleo.

"The time to apologize or have any remorse ... would have been when my husband was screaming he couldn't breathe," Esaw Garner told NBC's "Today" show.

Pantaleo said in a statement: "It is never my intention to harm anyone and I feel very bad about the death of Mr. Garner."

The officer's lawyer, Stuart London, told WCBS Radio that Pantaleo was trying to bring Garner to the ground because he feared they would crash through a storefront glass window in the struggle.

"He was attempting to do a takedown move that he was taught in the academy. He never meant to apply any force to his neck," London told WCBS Radio.

The city's medical examiner said police officers had killed the 43-year-old Garner by compressing his neck and chest, and ruled the death a homicide, adding that Garner's asthma and obesity had contributed to his death.

Chokeholds are prohibited by New York police regulations, but the Patrolmen's Benevolent Association, the municipal police union, said the officers involved in the Garner incident had acted within the law.

When the grand jury's decision was revealed, Garner's wife told the "Today" show: "I started crying because it's not fair. It's not fair. What could they not see? How could they possibly not indict?"

"I felt hopeless ... like there was nothing left for me to fight for but then I got some encouraging phone calls ... I felt now that we have some type of hope, some type of justice to be done for my husband," Esaw Garner said.

The U.S. Justice Department said it was investigating whether Garner's civil rights had been violated.

On Wednesday night, mostly peaceful protests sprang up throughout Manhattan, including atGrand Central Terminal, Times Square and near Rockefeller Center.

U.S. Attorney General Eric Holder told reporters in Washington that the Justice Department, which is already probing the circumstances of the Missouri shooting, would also examine the Garner case, as well as the local inquiry into it.

Brooklyn U.S. Attorney Loretta Lynch, whom President Barack Obama has nominated to succeed Holder and whose office will help lead the investigation, said in a statement on Wednesday the probe would be "fair and thorough."

Staten Island District Attorney Daniel Donovan, whose office oversaw the local investigation, said on Wednesday he had asked a judge to authorize the release of evidence that was presented to the grand jury, which like all grand juries operated in secret.

Missouri officials previously released the evidence considered by the grand jury in the Ferguson case.