Oglaigh na hEireann or the Continuity IRA, a splinter from the Irish Republican Army opposed to the peace process, made the claim, the Belfast Telegraph reported. The bomb, concealed in a sports bag, went off shortly before 7 p.m. Friday in the capital's trendy Cathedral Quarter.
The Police Service of Northern Ireland said witnesses reported the bag was left on a footpath by a man wearing a dark hooded jacket. Investigators said members of the public who reported the bag to police officers shortly before it detonated may have saved lives.
"Members of the public were vigilant and they did come forward and speak to police and it clearly averted injuries last night," Detective Chief Inspector Justyn Galloway said Saturday.
The Irish News got a warning phone call that said the bomb was in a hotel about 500 feet from the actual location, the Telegraph said. But police were able to refocus evacuations to the restaurant.
Chief Superintendent Alan McCrum said the bomb could have caused deaths or serious injuries.
"This was an attack on the people of Belfast going about their normal lives on a busy night for socializing in the city," he said. "This attack ruined the night out for these people. Those who carried out this attack have nothing to offer except disruption and destruction."
The bombing was the second in a few weeks aimed at the city center. In November, armed men in the Ardoyne neighborhood hijacked a car, loaded it with a bomb and ordered the driver to head into the center of Belfast. The driver was able to ditch the car and warn of the bomb, which exploded partially without injuring anyone.