A senior IMF official and four UN employees were among 21 people killed in a suicide bomb and gun attack on a restaurant in Kabul, officials say.
Wabel Abdallah, the head of the IMF's Afghanistan office, and the UN civilian staff died in what UN chief Ban Ki-moon said was a "horrific attack".
Canadians, Lebanese and a Briton were among the 13 foreign victims; the other eight were Afghans.
The Taliban said they carried out the attack late on Friday.
Five women were among the dead at the city's popular Taverna du Liban, and at least five were injured, police say.
A suicide attacker detonated his explosives outside the gate of the heavily fortified restaurant, Deputy Interior Minister Mohammad Ayoub Salangi said.
He said two gunmen then entered the restaurant and started "indiscriminately killing" people inside.
International Monetary Fund chief Christine Lagarde later confirmed that Wabel Abdallah, 60, a Lebanese national, was among those who died.
"This is tragic news, and we at the fund are all devastated," Lagarde said in a statement.
Meanwhile, UN Secretary General Ban Ki-moon condemned "in the strongest terms the horrific attack", his spokesman said.
"Such targeted attacks against civilians are completely unacceptable and are in flagrant breach of international humanitarian law. They must stop immediately," Ban was quoted as saying.
Separately, the UK Foreign Office (FCO) confirmed that a British national was among those killed in the incident and that it was ready to provide consular assistance to the person's family.
Kamal Hamade, the well-known Lebanese owner of the restaurant, and four women were among the dead. A number of people were injured.
"I was sitting with my friends in the kitchen when an explosion happened and smoke filled the kitchen," Abdul Majid, a chef at the restaurant, told AFP news agency.
"A man came inside shouting and he started shooting. One of my colleagues was shot and fell down. I ran to the roof and threw myself to the neighbouring property."
The attackers were eventually shot dead by the security forces when they arrived at the scene.
The BBC's Mahfouz Zubaide heard the blast and gunfire from at least two kilometres away. He said the gunfire went on sporadically for about 10 minutes.
The Taliban said it carried out the attack, saying it had been deliberately targeting foreign officials.
Security continues to be a major concern in Afghanistan. The last remaining contingent of Nato-led forces is due to leave by the end of the year, having handed over security to Afghan forces.
Washington is pushing Afghan President Hamid Karzai to sign an agreement which would allow some US troops to stay behind after this year's withdrawal.
The Taliban told the BBC's John Simpson earlier this week that it was now back in control of large areas of Afghanistan and was confident of returning to power after Western troops left.
Our correspondent says it is hard to believe the Taliban could make a comeback as things stand, but their takeover of Kabul in 1996 was unexpected, and they could be strengthened if a weak, corrupt president is elected in April.