WASHINGTON (AFP) - The White House on Saturday strongly condemned a Taliban suicide attack on a Kabul restaurant that killed 21 people.

"There is no possible justification for this attack, which has killed innocent civilians, including Americans, working every day to help the Afghan people achieve a better future," White House Press Secretary Jay Carney said in a statement.

Two Americans were among 13 foreigners who were killed when a suicide bomber detonated an explosive vest in the Taverna du Liban, clearing the way for two other militants who stormed into the restaurant and fired on survivors.

Also killed were eight Afghans, Kabul's police chief said.

The dead included employees of the United Nations, the American University, the International Monetary Fund and other organizations.

It was the deadliest attack on foreign civilians since the Taliban were ousted in 2001.

A Taliban spokesman said the attack was to avenge a US airstrike in Parwan province on Tuesday night that President Hamid Karzai said killed seven children and one woman.

"The United States commends the quick and skillful response of the Afghan security services in the aftermath of the attack.

"We call again on the Taliban to put down their arms and begin peace talks, which is the surest way to end the conflict in a peaceful manner," the White House statement said.