Assange held a live online chat session hosted by the British newspaper The Guardian. He did not confirm the source of the cables.
"For the past four years one of our goals has been to lionize the source who take the real risks in nearly every journalistic disclosure and without whose efforts, journalists would be nothing," Assange said. "If indeed it is the case, as alleged by the Pentagon, that the young soldier -- Bradley Manning -- is behind some of our recent disclosures, then he is without doubt an unparalleled hero."
Manning, a U.S. Army private who worked as an intelligence analyst in Iraq, has been charged with unauthorized release of information.
On a lighter note, Assange said WikiLeaks has received many documents about UFOs.
Assange had harsh words for Amazon.com, which stopped hosting WikiLeaks this week.
"Since 2007 we have been deliberately placing some of our servers in jurisdictions that we suspected suffered a free speech deficit in order to separate rhetoric from reality. Amazon was one of these cases," he said.
Assange, an Australian, currently faces a sexual assault charge in Sweden.