The White House on Monday condemned a deadly attack in Israel by a Palestinian suicide bomber and warned of grave consequences for the new Palestinian government led by Hamas, which defended the attack.

"It is a despicable act of terror for which there is no excuse or justification," White House press secretary Scott McClellan said.

"The burden of responsibility for preventing terrorist attacks such as this one rests with the Palestinian Authority," McClellan said. "We have noted reactions by several Palestinian terrorist groups, including Hamas, that defend or even applaud the barbaric act of terror committed in Tel Aviv today, as we have noted President (Mahmoud) Abbas' quick denunciation of it."

Abbas, of the rival Fatah Party, called the bombing a terrorist attack and said he ordered the Palestinian security forces to try to prevent more attacks.

"Defense or sponsorship of terrorist acts by officials of the Palestinian cabinet will have the gravest effects on relations between the Palestinian Authority and all states seeking peace in the Middle East," the White House spokesman said.

The bomber blew himself up outside a fast-food restaurant in a bustling area of Tel Aviv during the Passover holiday Monday.

It was the first suicide attack in Israel since the Hamas militant group took over the Palestinian government 2 1/2 weeks ago. The government called the attack a legitimate response to Israeli "aggression."

"A Palestinian government that encourages or tolerates terrorism against men, women and children not only increases the level of violence against Israelis, but can as well only do great harm to the interest of the Palestinian people and ensure its own further isolation," McClellan said.

"We reiterate that the United States will have no contact with such a government and we call upon all states to demand that it abandon its support for terror," the spokesman added.