"We're familiar with groups whose abuse we expose attempting to criticize the messenger," Assange told the Press Club in central London on Monday.
"We don't see any difference in the White House response to this case," added he referring to the White House fury over the leaks.
Assange urged greater transparency and said there was no reason to doubt the reliability of the documents.
"Just like any dealing with any source, you should exercise some common sense -- that doesn't mean that you should close your eyes," Assange said.
"We have no reason to doubt the reliability of these documents".
The Australian-born behind WikiLeaks had said earlier in June that he would release some videos of a secret Pentagon deadly airstrike on children in Afghanistan.
The whistle-blowing website also revealed a video showing the killing of two journalists and over a dozen civilians in a strike conducted by a US military Apache helicopter in Baghdad in 2007.
The link to the Wikileaks Afghan War Diary is: http://wardiary.wikileaks.org/