The defence department said the leak - one of the largest in US military history - put troops and Afghan informers at risk.
However, Julian Assange, the founder of Wikileaks, insisted that the website still planned to release its final batch of US military files , despite US demands it hold back.
Speaking via video link to an audience in London on Thursday, Assange said the site was preparing to release the final 15,000 classified files.
"We are about 7,000 reports in," he said, without giving a date when the files would be released.
Asked whether the website would press ahead with the release, he responded: "Absolutely."
The files contained a string of damaging claims, including allegations that Pakistani intelligence met directly with the Taliban and that deaths of innocent civilians at the hands of international forces were covered up.
The site, which styles itself as "the first intelligence agency of the people," was founded in December 2006 and invited would-be whistleblowers from around the world to make anonymous contributions.
WikiLeaks has never identified the source of the Afghan files but suspicion has fallen on Bradley Manning, a US Army intelligence analyst under arrest for allegedly leaking video of a 2007 US Apache helicopter strike in the Iraqi capital Baghdad in which civilians had died.