The incident occurred in a village in Deyak district on Wednesday when a helicopter operated by NATO forces fired on the police officers, said district police Chief Faiz Mohammad on Thursday.
Civilian casualties and mistaken killing of members of the Afghan security forces by foreign soldiers are a source of friction between President Hamid Karzai and the US-led NATO.
A spokesman for the NATO-led International Security Assistance Force (ISAF) said it was "assessing" the report.
"We're aware of local reports of an alleged air strike in Ghazni province yesterday in which several people were reportedly killed," the spokesman said.
Last week, an airstrike by NATO helicopter also killed two children in Ghazni province.
Many civilians have lost their lives in the US-led operations in various parts of Afghanistan over the past decade, with Afghans becoming increasingly outraged at the seemingly endless number of the deadly assaults.
Washington claims that its airstrikes target militants, but local sources say civilians have been the main victims of the attacks.