After releasing tens of thousands of confidential U.S. government cables, WikiLeaks would need $3.5 million over the next year to continue operating, Assange said.
Visa and MasterCard stopped processing donations for WikiLeaks in December 2010 after the United States criticized the organization's release of sensitive diplomatic cables.
"If WikiLeaks does not find a way to remove this blockade, given our current levels of expenditure we will simply not be able to continue by the turn of the year," Assange told a news conference.
The blocking of donations by Bank of America Corp, Visa Inc, MasterCard Inc, eBay Inc unit PayPal and Western Union Co had cost Wikileaks 95 percent of its revenue.
In July, WikiLeaks filed a complaint to the Directorate-General for Competition of the European Commission, saying Visa and MasterCard had breached antitrust provisions set out by the EU Treaty.
Assange said he hoped the European Commission would make a decision to hold a full investigation by mid-November.
(Reporting by Michael Holden; Editing by Roger Atwood)