"Well, I just want them to be sure, because it's a pretty serious charge, and I want them to be sure," Trump told reporters at his estate in Mar-a-Lago, Florida, AFP reported.
He noted that US intelligence had erred when it said Iraq possessed weapons of mass destruction -- the pretext for the US-led invasion in 2003 -- calling this "a disaster, and they were wrong".
He said it was "unfair" of the United States to accuse Russia of hacking if there was any doubt.
"And I know a lot about hacking. And hacking is a very hard thing to prove. So it could be somebody else. And I also know things that other people don't know, and so they cannot be sure of the situation," Trump said.
Asked what he knew that others did not, Trump said, "You'll find out Tuesday or Wednesday."
Trump was also asked how important cyber-security would be to his administration after he takes power on Jan. 20.
Trump said, "It's very important. If you have something really important, write it out and have it delivered by courier, the old fashioned way because I'll tell you what, no computer is safe. I don't care what they say, no computer is safe."