The bomber was on foot and jumped in front of a NATO military convoy in eastern Kabul, said Ali Shah Paktiawal, a senior police official.
The blast comes days after another suicide bomber killed 12 persons and wounded over 40 outside the Afghan Interior Ministry in the capital.
"I saw an American four wheel drive entering Kabul and suddenly a guy who was standing next to a pump station ran toward the vehicle and detonated himself," said Sayid Rahman, 22, an eyewitness. "That vehicle was damaged and they managed to flee from the area," Rahman said.
Three NATO-led troops received "minor injuries" and were evacuated to a nearby military hospital, said Maj. Luke Knittig, a NATO-led force spokesman. He would not disclose the nationalities of the soldiers injured.
Three other civilians were injured, Paktiawal said.
The attack occurred on the road frequently used by troops in the capital and the body of the bomber lay alongside two unexploded hand-grenades, an Associated Press reporter at the scene said.
On Sunday, a two-hour long clash between insurgents and police in the eastern Paktika province left two militants dead and four wounded, said Sayid Jamal, the governor's spokesman.
The bodies of those killed were turned over to the village elders while those wounded were being questioned by police, Jamal said.
Separately, a hand-grenade was thrown at a mosque in neighboring Nangahar province late Sunday, wounding seven people who were praying, said Ghafor Khan, spokesman for the provincial police chief.
Five persons were detained for questioning as authorities try to establish a motive for the attack, Khan said.