The Afghan president has been highly critical of civilian casualties
Afghan President Hamid Karzai is turning a new page in relations with the US, his spokesman has said.
The comments came as US President Barack Obama authorised up to 17,000 more US troops for Afghanistan.
Mr Obama has been critical of Mr Karzai and the phone call to inform him of the troop increase was believed to be the first since his inauguration.
Meanwhile, the US says it is checking claims that six women and two children died in an airstrike in Herat province.
"Mr Obama spoke with the president about various issues including steps for improving security in the region, equipment and training of the national army, further strengthening of bilateral relations, and the increase of forces was also discussed," Afghan presidential spokesman Humayun Hamidzada said.
"We have opened a new page."
Mr Obama said the 17,000 extra US troops had been due to go to Iraq but were being redirected to "meet urgent security needs".
"Afghan defence ministry spokesman Mohammad Ishaq Payman told the AFP news agency that the move was a "positive development".
"But we have our own conditions. We want these troops to be deployed in areas where they could play a positive role in suppressing terrorists," he said.
"We want them to be deployed along the border, in eastern, south-eastern and southern parts of the country."
It is the first major military decision by the Obama administration, and comes amid a major review of US policy in Afghanistan and Pakistan.
The additional troops are to be sent before warmer weather brings an expected increase in fighting in Afghanistan, US defence officials said.
They will be made up of 8,000 marines, and 4,000 army soldiers, plus another 5,000 support staff. They will serve in the south.
Relations between the US and Afghanistan have recently hit an all-time low, the BBC's Ian Pannell in Kabul says.
Well-placed leaks, briefs and snubs raised the prospect that Washington could move its support away from Mr Karzai in this year's presidential poll.
Mr Karzai in turn has become increasingly vociferous in his criticism of American military tactics and of the rise in civilian casualties in particular.
He has repeatedly warned that his people are losing patience over the continuing casualties.
On Tuesday, the UN said that 2,118 civilians were killed in the conflict in 2008 - an increase of 39% from 2007.
Militants were to blame for 55% of the deaths, while US, Nato and Afghan forces were responsible for 39%, the UN said.
In the latest incident, the US says it is investigating reports that civilians died in an airstrike in the Gozara district of Herat province.
The US says it killed 15 militants, including a leader named Ghulam Yahya Akbari who was "responsible for a terror campaign throughout Herat using kidnapping and murder to brutalise Afghan civilians and village elders".
Officials in the area say that six women and two children were among 16 people who were killed - and that 15 of the dead were civilians.
US officials say that a combined coalition and Afghan team along with international observers visited Gozara on Wednesday as part of the "post operation strike investigation related to the targeting of an insurgent leader in the province".
US military spokesman Lt Col Rick Helmer said: "We take all reports of non-combatant casualties very seriously.
"If it is discovered that any non-combatants were killed or injured in the strike we will take responsibility and make amends.
"However, it has been a past practice of the insurgents to surround themselves with women and children, knowingly placing them in danger."