Six US soldiers have been disciplined for the incineration in February of up to 100 Korans and other religious texts in Afghanistan, the US military said.
They will not face criminal prosecution over the incident, which sparked rioting that claimed at least 30 lives and saw two US troops shot dead.
The investigation said there was no malicious intent to disrespect Islam.
Three US Marines were also disciplined for a video in which the bodies of dead Taliban fighters were urinated on.
For the Koran burning, the six soldiers face "administrative punishments" that could include measures like reduction of rank, extra duty or forfeiture of pay. They are four officers and two non-commissioned officers.
In the wake of the 20 February incident, Afghan President Hamid Karzai called for a public trial of the soldiers involved.
His office told the Associated Press news agency Mr Karzai would review the decisions and respond on Tuesday.
The findings showed that up to 100 Korans and other religious texts - a previously undisclosed figure - had been incinerated at Bagram Air Field, a US air base north of Kabul.
Some 53 Korans and 162 other religious books were recovered from the incinerator. All of these texts had been damaged by fire, and about one-third of them were "slightly damaged", according to the report.
They had been removed from the Parwan Detention Centre amid concerns that detainees were using the books to pass secret messages.
A translator was partly blamed in the report for apparently having suggested that most of the texts were extremist in nature, without instructing American forces how to properly dispose of the books.
The report added that warnings from Afghans, including an Afghan soldier, had been ignored - something the investigation attributed in part to distrust between the US troops and Afghans.
But Brigadier General Bryan Watson, the investigating officer, wrote: "I absolutely reject any suggestion that those involved acted with any malicious intent to disrespect the Koran or defame the faith of Islam."
The investigation's findings came on the same day the US Marine Corps announced its punishment for three servicemen who took part in a video in which the bodies of dead Taliban fighters were urinated on.
Three servicemen pleaded guilty: one to "urinating on the body of a deceased Taliban soldier", another to posing for a photo with human casualties, and a third for lying to investigators.
In the video, someone can be heard saying: "Have a good day, buddy."
Their identities have not been revealed and the Marine Corps said it would provide details of disciplinary actions against them at a later date.