Iraq has demanded that the US end its association with private security firm Blackwater within six months.
The shooting left 17 Iraqi civilians dead and more than 20 wounded
It accuses Blackwater guards of having deliberately fired on Iraqi civilians, killing 17 and injuring more than 20.
The government has demanded Blackwater pay $8m compensation to each family bereaved by last month's shootings.
Private security employees are immune from prosecution in Iraq, but an FBI investigation into the killings raises the prospect of trials in the US.
The BBC's Jon Brain in Baghdad says the now infamous Blackwater affair is continuing to cause huge strains between the Iraqi and US governments.
The new details of Iraq's demands were outlined in an official report issued on Monday in Arabic and subsequently translated by international news agencies.
Blackwater denies its men acted improperly, while Washington, which depends on the company to protect its embassy staff in Baghdad, has declined to comment on the Iraqi report.
The report says in the time since Blackwater took over security for US diplomats in 2003, its guards have killed 38 Iraqi civilians and wounded about 50 in shootings.
BLACKWATER USA FACTS
Founded in 1997 by a former US Navy Seal
Headquarters in North Carolina
One of at least 28 private security companies in Iraq
Employs 744 US citizens, 231 third-country nationals, and 12 Iraqis to protect US state department in Iraq
Provided protection for former CPA head Paul Bremer
Four employees killed in Falluja in March 2004
It also says Blackwater's licence to operate in Iraq expired in 2006, meaning it had no immunity from prosecution under the laws introduced by the US authorities in Iraq after the 2003 invasion.
The Iraqi panel led by the defence minister calls for the US to hand over Blackwater guards to face possible trial in Iraqi courts.
The report says that on 16 September four Blackwater vehicles and two helicopters opened fire without provocation in two locations after a car bombing near a meeting involving a USAID official under Blackwater protection.
At least 14 Iraqi civilians were killed in Nisoor square, and two or three more were killed at the next intersection, the report says.
The compensation requested is higher than usual "because Blackwater uses employees who disrespect the rights of Iraqi citizens even though they are guests in this country", the report said, as quoted by Associated Press.
Blackwater has not responded to the Iraqi government investigation but insists its employees came under fire first.
Blackwater is the main firm employed by the US state department to provide security for its staff in Baghdad and visiting officials and businessmen.
In the days following the incident, which caused widespread anger in Iraq, the interior ministry drafted legislation bring private security contractors under Iraqi law.