Assange has been holed up at the Ecuador embassy in London after claiming asylum from that country a year ago to avoid extradition to Sweden, where he is wanted for questioning over allegations of sexual assault against two women.
Cumberbatch plays the controversial hacker in director Bill Condon's "The Fifth Estate," which opened the Toronto film festival yesterday evening.
"It's very complicated, and it's to do with dealings and goings-on behind closed doors and I don't have access to any kind of information or perspective that would shine a light on some certain truth about that," Cumberbatch told a press conference.
Condon added that the man behind the largest secrets leak in American history in 2010 is "an absolute pioneer and he's made a huge difference. He opened the door that Edward Snowden just walked through. For all of those reasons, I think he's an extremely admirable figure.
"It becomes a question when there's so much information that he is responsible for and whether he is the person or kind of person that we want to leave that responsibility to."
In the wake of that controversy, contractor Edward Snowden disclosed details of the National Security Agency's secret electronic monitoring operations, and then fled to Russia.
Assange himself has panned Condon's film, saying it is "a lie upon a lie" but Condon said those comments were based on an early script "which really bears little resemblance to the movie we made."
Cumberbatch added, "I didn't want to impersonate Julian but interpret(him).