Afghan forces are engaged in a gunbattle with the Taliban after the militants attacked a large military base in southern Helmand Province late on February 28.
The Afghan Defense Ministry said on March 1 that four militants had been killed in the raid on the base where some U.S. military advisers and soldiers are also stationed.
According to the ministry, there were casualties among Afghan forces, but no exact figures were given.
On Twitter, U.S. military spokesman Colonel Dave Butler said the attack "was repelled by the brave Afghan Security Forces."
Butler later added that reports indicated "Taliban fighters were initially able to gain access to the Afghan base but were stopped by Afghan forces."
The Taliban said its fighters had killed dozens of Afghan soldiers.
A military source told RFE/RL that a top Afghan commander at the military installation had been killed in the attack.
The assault on the base comes with the U.S. peace envoy for Afghanistan in Qatar for the latest round of peace talks.
On February 28, Zalmay Khalilzad said negotiations would resume on March 2 following three days of talks with Taliban negotiators in Doha, aimed at finding a negotiated solution to Afghanistan's 17-year war.
In the past, Khalilzad has tried to convince the Taliban to hold direct talks with representatives of Afghanistan's government. The Taliban has rejected that proposal.
In Kabul on February 28, Afghan President Ashraf Ghani reiterated that an Afghan-led peace process would provide lasting stability in the country.
"Afghanistan wants cooperation and collaboration, but Afghans and the legitimate government of Afghanistan should own the peace process," he said.
With reporting by dpa and AFP