"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 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 US State Department said the IMF's resident representative, Wabel Abdallah, was among those killed.
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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 restaurant attack -- the deadliest on foreign civilians since the Taliban were ousted in 2001 -- comes as a US-led NATO force is to withdraw from the country by the end of the year.
"The United States commends the quick and skillful response of the Afghan security services in the aftermath of the attack," the White House statement said.
"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," it said.