Talk of a stop-over in the United States by the Taiwan president has further rattled Washington-Beijing relations.
On another foreign policy matter, Trump warned against being quick to pin the blame on Russia for the hacking of U.S. emails. The Washington Post also reported on Friday that Moscow could be behind intrusion into a laptop owned by a Vermont electric utility.
U.S. intelligence officials have said that they are confident Russia was behind the hacks of political figures, which could have played a role in Trump's defeat over Democratic presidential candidate Hillary Clinton.
"I think it's unfair if we don't know. It could be somebody else. I also know things that other people don't know so we cannot be sure," Trump said.
Asked what that information included, the Republican President-elect said, "You will find out on Tuesday or Wednesday."
He did not elaborate.
But he said that any computer is subject to hacks.
"It's very important. If you have something really important write it out and have it delivered by courier the old fashioned way," Trump said, adding, "No computer is safe, I don't care what they say."
Trump tried to end the year on a positive note, however, despite questions about the future of U.S.-Russia relations because of escalating tensions between Obama and Russian President Vladimir Putin, as well as Trump's promise to crack down on China's trade practices, which he says unfairly target American workers.
"Hopefully we're going to have great relationships with many countries and that includes Russia and that includes China," Trump said.
But he criticized U.S. Secretary of State John Kerry for earlier this week offering a stark assessment of Israel's policies in the Middle East, which he said could threaten the possibility of establishing a Palestinian state co-existing with Israel.
Trump called Kerry's speech "very unfair."
As he wrapped up a four-minute informal chat with reporters, Trump also was asked what his 2017 new year's resolution was.
"Make America great again," he said.