The suspected cross-border attack took place in Kam Sam village in the North Waziristan region, a stronghold of Taliban and al Qaeda militants blamed for attacks on U.S. troops in Afghanistan and rising violence within Pakistan.
One Pakistani security official said 10 people died. Another put the toll at eight. The identity of the victims was not clear and it was not immediately possible to reconcile the differing tallies.
Both officials spoke on condition of anonymity because they were not authorized to speak to the media. They said they received information from informants and agents on the ground.
Unmanned U.S. aircraft are believed to have carried out at least 18 missile strikes in Pakistan since August, triggering anger from the Muslim country's civil and military leaders, as well as many of its 170 million people.
The attack was the first since the installation of Gen. Petraeus as head of U.S. Central Command on Oct. 31, giving him overall command of the wars in both Iraq and Afghanistan.
Pakistani leaders said they told Petraeus to stop the cross-border strikes when he visited the country earlier this week. He said he would "take on board" what they said, but gave no promise the attacks would stop.
Similar U.S. strikes on the Afghan side of the border have drawn increasingly sharp rebukes from that country's leadership in recent weeks as the civilian death toll climbs.
An airstrike in northwest Afghanistan killed 13 Taliban militants and seven civilians Thursday, Afghan officials said, a day after President Hamid Karzai demanded a halt to civilian casualties in U.S.-led coalition operations.
The United States has conducted missile strikes in Afghanistan and in Pakistan's tribal areas along the border - strikes Gen. Petraeus said Thursday have killed three of the top 20 extremist leaders there.
The strike came just days after another coalition airstrike in the south of the country, mostly woman and children.