"Nothing has occurred so far," one law enforcement official told The Washington Post, noting a grand jury investigation remains open. "But it's subject to change. I can't predict what's going to happen. The investigation is ongoing."
A spokesman for WikiLeaks said it is encouraged a sealed indictment has not been filed.
"We will treat this news with skepticism short of an open, official, formal confirmation that the U.S. government is not going to prosecute WikiLeaks," spokesman Kristinn Hrafnsson said.
Assange has been living in the Ecuadoran Embassy in London since 2012 when he was granted political asylum.
WikiLeaks received classified U.S. documents from Pfc. Bradley Manning in 2010 and the organization published the material.
After Manning was convicted, a spokesman for the U.S. attorney's office said a grand jury investigation was ongoing, but would not comment on whether a sealed indictment had been filed.
Officials indicated prosecutors are treating Edward Snowden differently due to his status as a government employee.
"Snowden was a person who swore an oath, an employee of the National Security Agency," a second senior U.S. official told the Post.
Snowden has been charged under the Espionage Act for releasing thousands of documents about U.S. surveillance programs.