A statement issued in reply to a query by AFP said an investigation into the August 13 incident in a predominantly Shiite neighborhood of Baghdad concluded that "poor judgment was employed by those soldiers implicated in the action."
"Administrative actions have been initiated against those service members involved," said the statement sent by the press desk of the Coalition Press Information Center in Baghdad.
It did not say how many soldiers were facing punishment or the nature of the sanctions that might be imposed. A military spokesman, contacted by AFP, was unable to provide any further details.
Tensions had boiled in Baghdad's vast and impoverished Sadr City district after the incident sparked by an American helicopter that apparently tried to remove a black religious flag from a communications tower.
US troops fired into a crowd of thousands of enraged protesters, killing an Iraqi and wounding four other people. The army said it had been attacked with rocket-propelled grenades (RPGs), guns and stones.
But US military officials issued a letter of apology to the Shiite Muslim community for the incident and promised to discipline the soldiers responsible.
"Apparently the helicopter either blew down the flag or somehow that flag was taken down," Lieutenant General Ricardo Sanchez, the commander of US ground forces in Iraq, said at the time.
"We are taking steps to ensure that doesn't happen again," Sanchez said. "Our intention is not to alienate the Shiite people."
"We deeply regret what happened today (Wednesday, August 13)," said a letter signed by Christopher Hoffman of the 2nd Armored Cavalry Regiment, a copy of which was provided to AFP by a Shiite cleric.
"What happened was a mistake and was not directed against the people of Sadr City. I am personally investigating this incident and will punish those that are responsible," Hoffman said in the letter.
He also promised to reduce the number of helicopter and ground patrols in Sadr City and offered to meet clerics to discuss what he called "reimbursement."
The US military routinely announces the launch of investigations into alleged wrongdoing by its troops in cases of civilian deaths in Iraq, but unveils the results of the inquiries much less frequently.
Despite repeated queries, the military has yet to say how many US soldiers in Iraq have been discplined. Asked again Friday, Sergeant Nicole Thompson, a spokeswoman, said "I'll have to refer that to our research department."
The military did announce Thursday the results of two investigations, clearing its troops of any guilt for a pair of shooting incidents this month and last that killed Iraqi security personnel.
Nine Iraqi security men and a Jordanian guard were killed September 12 by US fire in the town of Fallujah. Two Iraqi policemen were shot dead August 10 in Baghdad, including one who was reportedly trying to surrender.
In both cases, the military concluded the American troops had "acted within the rules of engagement." No further details of either inquiry were released, sparking concern among human rights groups about a lack of transparency.
The same formulation was used in exonerating US troops who shot and killed Reuters TV cameraman Mazen Dana, mistaking his camera for an RPG launcher as he was videotaping near a prison last month.
The ruling prompted a protest from Tom Glocer, the chief executive of Reuters, who complained to US Defense Secretary Donald Rumsfeld that the Pentagon failed to provide proper information about its investigation.
In a statement Friday urging world leaders to set aside their political differences to restore law and order in Iraq, Amnesty International said, "No one feels safe in Iraq now and not a day goes by without more civilians being killed or injured by US soldiers or by armed groups amidst total impunity."
"What is most shocking is that there is no evidence of serious commitment to carry out independent, thorough and impartial investigations into these cases," it said.