Vice-President Joe Biden told President-elect Donald Trump Thursday to "grow up."

Biden dismissed a Trump complaint on Twitter about how the Obama administration has handled the transition. The vice-president told "PBS NewsHour" in an interview: "Grow up, Donald. Grow up. It's time to be an adult."

Biden said of Trump: "You're president. You've got to do something. Show us what you have."

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The vice-president also said that Trump as president will have to propose legislation that Congress and the public can then assess. He said that it'll be "much clearer what he's for and against" once he's in the position of governing.

Biden also said it's "dangerous" for Trump to have publicly criticized the U.S. intelligence community over its conclusion that Russia interfered in the November election. Biden said it's "absolutely mindless" for a president not to have confidence in or listen to intelligence agencies.

The vice-president said it would be legitimate to question intelligence and ask for more detail or disagree. But he said that's different than Trump claiming he knows more than the intelligence agencies.

Biden said that's like saying, "I know more about physics than my professor." He says that's worrisome, but he assumes Trump's behaviour will change. He said that Trump is surrounding himself with "very smart people" like retired Marine Corps Gen. James Mattis, the billionaire businessman's pick for defence secretary.