"I can confirm that two American personnel of the US embassy were slightly hurt while on a routine embassy mission near Kabul," Michael Macy, a US embassy public affairs officer, said.
He declined to identify the pair and also refused to say if the US ambassador to Afghanistan, Ronald Neumann, was in the convoy during the blast.
US soldiers killed
Earlier on Sunday, a roadside bomb attack in southern Afghanistan has killed four US soldiers and wounded three others, the US military said.
A blast occurred as the troops were patrolling in Zabul province's Daychopan district, the military said in a statement on Sunday.
The three wounded were wounded in secondary blasts as they were trying to pull their colleagues out of an armoured Humvee that had been hit by the bomb, it said.
Afghan elections are scheduled
for next month
A purported Taliban spokesman, Abdul Latif Hakimi, speaking by telephone from an undisclosed location, claimed the attack, saying Taliban fighters had planted the improvised explosive device, Reuters reported.
The three wounded soldiers were evacuated to a nearby base and treated for shrapnel wounds. They were in stable condition, the statement said.
"The unit was conducting offensive operations in support of an ongoing mission to find and defeat enemy forces in the area when the attack occurred," the statement said.
"The unit's mission is part of a much larger operation to disrupt enemy forces and to thereby provide a safe environment for upcoming September elections," it said.
The statement quoted Major-General Jason Kamiya, the US-led coalition's operational commander, as saying the attack would "strengthen, not weaken, the resolve" of the force.
"We mourn the tragic loss of our fallen soldiers and will continue to remember them, their families and loved ones in our thoughts and prayers," he said.
US forces have suffered 47 deaths in combat in Afghanistan this year, making it the worst period since they arrived to oust the Taliban in October 2001.