Assange, speaking Tuesday from the London-area home where he's staying as part of his bail agreement, said he doesn't feel obliged to be "at the beck and call of people making allegations" against him and there were "serious problems" with the prosecution against him.
"The law says that I also have certain rights, and these rights mean that I do not need to speak to random prosecutors around the world who simply want to have a chat, and won't do it in any other standard way," The Guardian quoted Assange as saying.
He said he was available for weeks for questioning about the sexual assault claims made by two women, but heard nothing from the Swedish authorities. Assange added he was told there was no reason for him to stay in the country.
"If they want to charge me, they can charge me. They have decided not to charge me," Assange said. "They have asked, as part of their application, that if I go to Sweden and am arrested, I am to be held incommunicado. They have asked that my Swedish lawyer be gagged from talking to the public."
Assange surrendered to London police Dec. 6 and was arrested on a European warrant from Sweden where prosecutors want to question him about the allegations, which he denies. He was freed on $376,000 bail last week.
The Swedish matter against Assange is separate from his role in releasing more than 250,000 U.S. State Department documents, some of which were published in select newspapers, including The Guardian.
He said WikiLeaks "changed governments -- we have certainly changed many political figures within governments."
Assange told the BBC his mission was "to promote justice through the method of transparency."
"The world has a lot of problems that need to be reformed," he said, "and we only live once."
In an interview with The Times of London, Assange accused The Guardian of "selectively publishing" material from Swedish prosecutors.
The Guardian said it was allowed access to witness statements held by Swedish prosecutors and understood Assange's defense team saw the documents.
"The leak of the police report to The Guardian was clearly designed to undermine my bail application," Assange told The Times. "It was timed to come up on the desk of the judge that morning. Someone in authority clearly intended to keep Julian in prison."