Government officials travelled to the area to investigate after residents said up to 110 people were killed.
Ali Shah said of Friday's strikes: "The finding of our investigations about the civilian casualties in Gereshk district so far is that 65 civilians including women, children and men have been killed."
Nato's International Security Assistance Force (Isaf) and the US-led coalition said they were investigating the reports.
Major John Thomas, an Isaf spokesman, said: "One civilian who dies is one too many. When we have this situation, almost every one of these deaths is in response to enemies firing at us and then hiding themselves amongst civilians."
"In return fire, in self-defence, then we find out that they were amongst civilians."
"We are here at guests of the Afghan people and the Afghan president … even when the Taliban are playing these brutal tricks."
"We're not going to adjust the rules of engagement, because they're good, they're firm and they're fair … [But] we are trying to respond to the way the Taliban are adjusting their tactics"
Nick Lunt, Nato civilian spokesman
Nick Lunt, Nato's civilian spokesman, said: "It's pretty clear that Taliban extremists are going to measure success in terms of the number of civilians that they actually kill themselves or are being forced into areas of conflict.
"We're not going to adjust the rules of engagement, because they're good, they're firm and they're fair … [But] we are trying to respond to the way the Taliban are adjusting their tactics.
"We know the support of the people is absolutely critical to what we do."
Four people were earlier killed in an air strike launched by the US-led coalition forces in the eastern Nangarhar province.
A coalition force statement had said that those killed were Taliban fighters and that no civilians were injured in the strike.
However, the Afghan human rights group said that the four killed were all civilians who belonged to the same family.
Civilian deaths caused by US and Nato-led troops have infuriated Afghans and prompted Hamid Karzai, the president, to publicly condemn foreign forces for carelessness and viewing Afghan lives as "cheap".
He urged restraint and better coordination of military operations with the Afghan government, while also blaming Taliban for using civilians as human shields.
Violence has soared in Afghanistan with more than 2,800 people killed in fighting this year, according to an Associated Press tally of figures from Western military and Afghan officials.
A count by the United Nations and an umbrella organisation of Afghan and international aid groups shows that the number of civilians killed by international forces was slightly greater than the number killed by suspected Taliban fighters in the first half of the year.
An AP count for 2007 based on figures from Afghan and international officials found that while fighters killed 178 civilians in attacks through June 23, Western forces killed 203. The US and Nato say they don't have civilian casualty figures.
|The number of those killed and injured in |
Friday's attack is still not fully known
Also in the south, two suspected Taliban were killed while trying to place an improvised explosive device on the side of a road in Zhari district in Kandahar province, said Ghulam Rasool, the district's police chief.
The roadside bomb exploded while it was being planted, killing the two men on Friday, Rasool said.
Three children were also killed on Friday and another wounded when an old rocket they were playing with exploded in Zabul province in the south, said General Yaqoub Khan, the provincial police chief.