Assange also reiterated allegations made in Wednesday's publications that the U.S. consulate in Frankfurt, Germany served as a base for U.S. cyber warriors.
The CIA has not confirmed the authenticity of the documents, but officials tell ABC News that they appear authentic.
Questions have been raised in recent months over the role that WikiLeaks played in Russian efforts to undermine the 2016 U.S. election.
In a January interview with Fox News, Assange said, "We can say – we have said repeatedly – over the last two months that our source is not the Russian government and it is not a state party."
Asked via Twitter by ABC News' Brian Ross whether he had ever been paid by the Russian government or its state-funded RT television network, Assange said "no," before dismissing the question saying it was a "pretty sad question trying to divert from this epic publication to yeah, something else."
In August, the New York Times reported that RT – previously known as Russia Today – "began broadcasting a show called 'The World Tomorrow' with Mr. Assange as the host," but added that, "how much he or WikiLeaks was paid for the 12 episodes remains unclear."
Anna Belkina, a spokeswoman for RT, told ABC News on Thursday that she would not disclose what compensation Assange may have received for the 12-episode interview program he produced in 2012.
“The contract details are confidential,” she said.
In Thursday's press conference, Assange made the claim that the CIA became aware "within the last couple of months that it had lost" the documents his organization published on Wednesday. He raised questions about who in the U.S. government knew that the documents were no longer secure – and when – and alleged that the agency "appears to have covered up," its loss of the top secret materials.
He also pondered whether the CIA had told former President Barack Obama about the the document leak – a seeming admission that he believed the CIA lost control of the documents months ago. WikiLeaks claims the documents are from 2013 to 2016.
In a press release accompanying the published documents on Wednesday, WikiLeaks suggested that their source was a government contractor.
In the press conference on Thursday, Assange went slightly further, saying, "our sources stepped forward to us," but added that, "we can’t comment directly on sourcing."
Assange said that his organization had not published details or schematics of any actual cyber weapons out of an interest to protect journalists, its sources and others from falling victim to them.
The press conference was streamed live on Facebook and Periscope.
Assange was speaking from the Ecuadorian Embassy in London where he has lived since 2012.
ABC News' Alex Hosenball, Cho Park, Taylor Harris and Laura Sanicola contributed to this report.