Hundreds of villagers in the Afghan province of Nangarhar are protesting over a Nato raid on Thursday, which they claim killed several civilians.
There is no independent confirmation of the death toll but local estimates vary from six to 11 dead.
Nato officials confirmed an operation targeted a Taliban hideout, but said they were not aware of civilian deaths.
Civilian casualties at Nato hands are the source of increasing friction between the Afghan government and Nato.
Afghan President Hamid Karzai is on a visit to the US, part of an effort to repair the rocky relations between Kabul and Washington.
On Thursday he paid his respects to US troops killed in Afghanistan at Arlington National Cemetery. He is also expected to visit Fort Campbell, the base of a US military division set to travel to Afghanistan.
In a joint news conference with President Karzai on Wednesday, US President Barack Obama said that US forces would try not to harm civilians in their operations.
Coalition forces are planning a major assault in the southern province of Kandahar, a key stronghold of Taliban insurgents.
But President Obama also backed Afghan plans to "open the door" to Taliban militants who renounce violence and cut ties with al-Qaeda.
A Nato statement said that a Taliban sub-commander and other insurgents were killed and two insurgents captured during the raid, in the Surkh Rod district in Nangarhar province.
But villagers burned tyres and blocked roads in the area as they insisted that civilians were among the dead and that two more were taken alive.
"They are farmers. They are innocent. They are not insurgents or militants," Mohammed Arish, a local administrator in the district told the Associated Press news agency by telephone.
Some unconfirmed reports say there were clashes as police stopped protesters marching to the provincial capital of Jalalabad.
In late April, a prominent Afghan MP accused Nato troops of storming her home in Surkh Rod district and shooting dead one of her relatives.
Safia Siddiqi was not home at the time but said soldiers tied up members of her family and fired at one. Nato said one person was killed in an operation against a "Taliban facilitator" .
Since taking up his position as top commander in Afghanistan, Gen Stanley McChrystal has said reducing civilian casualties is a key priority for Nato.
He has introduced changes to Nato tactics aimed at cutting the risks to civilians. Measures include reducing the number of air strikes and night raids.