During the US hunt for Snowden, President Morales' plane was forced to land in Austria for 14 hours after Spain, France, Portugal and Italy closed their airspace under pressure from the US.
Once grounded in Vienna, Austrian officials searched the jet for Mr Snowden, but he was not on board.
In an exclusive interview Assange spoke to Democracy Now from the Ecuadorian Embassy in London, where he has been living for nearly three years.
In 2013, he played a central role in helping Edward Snowden leave Hong Kong for Russia.
Assange told Democracy Now that they had considered flying Snowden out of Moscow into Latin America on a presidential jet. “There was an international oil conference in Moscow that week. Edward Snowden and our journalist, Sarah Harrison, were still in the Moscow airport in the transit lounge, and so we thought, well, this is an opportunity, to send Edward Snowden to Latin America on one of these jets.”
He added that his team used code when talking about the planned operation. “We just spoke about Bolivia in order to distract from the actual candidate jet. And in some of our communications, we deliberately spoke about that on open lines to lawyers in the United States. And we didn't think much more of it.”
But he said that security agents were listening in to the conversations and the US then put pressure on France, Portugal and Spain to close their airspace to President Morales's jet in its flight from Moscow to the Canary Islands for refueling, and then back to Bolivia.
President Morales had previously said his country would consider a request for political asylum from Snowden. He later described the grounding incident as "almost a kidnapping".
“It's really a quite extraordinary situation that reveals the true nature of the relationship between Western Europe and the United States and what it claims are its values of human rights and asylum, and respecting the rule of law,” Assange told Democracy Now. “Just a phone call from US intelligence was enough to close the airspace to a booked presidential flight, which has immunity. And they got it wrong.”
Assange goes on to say that this incident became a key ingredient in Edward Snowden's asylum application in Russia, as it helped prove that he was unlikely to receive a fair trial in the United States.
Snowden is wanted by the US on charges of leaking secrets he gathered while working as a contractor for the NSA, America's electronic spying agency.