"Last night's deadly siege in a central Kabul hotel is a stark reminder of the Taliban's contempt for human life," it said.
Four Indians, two Pakistanis and an American were among the 14 people killed in the attack, with a top Afghan official saying the Indian Ambassador could have been the target of the militants who stormed the complex popular among expats.
"There has been a worrying spike in assaults carried out by the Taliban and other armed groups on 'soft targets' across Afghanistan in recent weeks - of which this is just the latest attack - resulting in a high civilian death toll," she said.
According to Agency Coordinating Body of Afghan Relief and Development (ACBAR), seven humanitarian workers were among those killed in last night's attack.
UNAMA said such "deliberate attacks on civilians are atrocities."
The agency recently stated the Taliban and other armed groups are responsible for almost three-quarters of all civilian deaths in Afghanistan.
"The Taliban are well aware of their obligations under international humanitarian law, but they only refer to it when it suits them. The Taliban must immediately end their brutal practice of targeting and killing civilians and abide by the rules of war," said Horia Mosadiq.
