At least 10 people were killed and 19 injured after a blast in front of a British security compound on Wednesday, officials said.
A Taliban suicide bomber detonated explosives in front of security firm G4S' site in eastern Kabul.
A gun battle between other insurgents and security forces unfolded shortly after, Afghanistan Interior Ministry spokesperson Najib Danish said.
The Taliban, who have taken over nearly half of Afghanistan in recent years, claimed the attack in a statement posted on Twitter.
The assault came hours after 30 civilians were killed in an overnight battle between Afghan forces and Taliban fighters in southern Helmand province.
A G4S spokesperson confirmed five of their employees were killed in the "unprovoked, criminal attack," including one British national.
"We are committed to our security role in support of the people of Afghanistan, and we are determined that incidents such as this will not prevent the vital work that the international community conducts from continuing," Charlie Burbridge, Managing Director of G4S, said.
US and NATO troops formally concluded their combat mission in Afghanistan in 2014, but still provide close support to Afghan forces and carry out counterterrorism operations.
Some 15,000 American forces are currently serving in Afghanistan, AP reports.