Afghan officials have said that 140 civilians were killed during air raids in the province of Farah earlier this month.
The US military says about 30 civilians and 60 to 65 Taliban fighters were killed during the operations.
The review said the early May air raids were carried out against Taliban targets in Farah but that, at least in one case, it was unclear whether civilians were in the vicinity.
In one incident, an Air Force B-1 dropped a 900kg bomb on a building that Taliban fighters had been seen entering, officials say.
Some military officials have questioned whether that bomb was larger and more destructive than warranted, the Associated Press reported.
|Afghans have expressed outrage at
civilian deaths from US bombing [Reuters]
The air crew received permission to strike, but circled around and dropped the bomb without reconfirming, the report is set to say.
That delay, officials said, may have allowed the fighters to leave the building and civilians to enter before the bomb was dropped.
It is not known whether that raid added to the civilian toll, officials have said.
Officials said the report does not recommend changes in tactics and procedures used in Afghanistan, though the new commander there, Lieutenant-General Stanley McChrystal, has said he will review them as well as all existing rules of engagement.
The US government has come under increasing criticism over the past year for civilian deaths during operations against Taliban and al-Qaeda fighters in Afghanistan and Pakistan.
Barack Obama, the US president, and other Washington officials have repeatedly expressed regret for civilian casualties and vowed to take measures that would avoid future attacks.