In the second incident on Saturday, a tribal leader died after soldiers opened fire on his vehicle in the eastern province of Paktia.
The shooting occurred after they moved too close to a military, ignoring warnings to stop, an Isaf statement said.
Another passenger in the vehicle was wounded in the attack.
Civilian casualties have eroded public support for foreign forces operating in Afghanistan and the government of Hamid Karzai, the country's president.
Karzai has demanded that US and Nato forces do more to stop civilian deaths during their operations.
In yet another incident on Sunday, three French people were injured in a suicide car bomb attack on a French military convoy in Kabul.
The blast took place in the southwestern outskirts of the Afghan capital, on a road that leads to the Wardak province.
The injured were a French soldier and two civilians, France's interior ministry said.
The Taliban claimed responsibility for the attack, according to the Reuters news agency.
There have been regular suicide attacks in Afghanistan where about 70,000 international troops are deployed.
About 30,000 more US soldiers are expected to be sent to Afghanistan in 2009 as Barack Obama's administration plans to shift its foreign policy focus away from Iraq.