No casualties were immediately reported from the bombing, which sent a thick plume of smoke rising into the sky, as the Taliban ramp up attacks on government and foreign targets.
Security officials cordoned off the area as ambulances with wailing sirens rushed to the scene, which was littered with the mangled wreckage of vehicles, according to an AFP photographer.
"The explosion occurred in the Joy Shir area of Kabul city. It was a suicide attack targeting a foreign forces convoy," Kabul police spokesman Ebadullah Karimi told AFP.
A NATO spokesman in Kabul confirmed that their convoy came under attack but said the international coalition was still gathering further information.
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The Taliban were behind the bombing, the group's spokesman Zabihullah Mujahid told AFP.
"A convoy of foreign forces came under martyrdom attack by our mujahideen in Joy Shir area of Kabul city. Two of their vehicles were damaged and all aboard the vehicles were killed," he said.
The Taliban, toppled from power in a 2001 US-led invasion of Afghanistan, are known to exaggerate battlefield claims.
The militants overran the strategic northern city of Kunduz in late September, in their most spectacular victory in 14 years.
The capture of the provincial capital for three days marked a stinging blow for Western-trained Afghan forces, who have largely been fighting on their own since the end of NATO's combat mission in December.
The government claims to have wrested back control of the city but sporadic firefights continue with remnant pockets of insurgents as Afghan soldiers, backed by NATO special forces, conduct clearance operations.
Most NATO combat troops pulled out of Afghanistan last year but a small contingent focused on training and counter-terrorism operations remains, including roughly 10,000 American soldiers.
NATO forces are themselves under fire after a US air strike on October 3 pummelled a hospital in Kunduz run by Doctors Without Borders (MSF), killing 12 staff and 10 patients.
The medical charity shut down the trauma centre, branding the incident a war crime and demanding an international investigation into the incident, which sparked an avalanche of global condemnation.