US Vice-President Joe Biden has told Donald Trump to "grow up" as he condemned the president-elect for criticising US intelligence officials.
Mr Biden spoke out amid reports that intelligence agencies had identified Russian parties who delivered stolen Democratic emails to WikiLeaks.
The Washington Post, citing anonymous US officials, reported there were clear disparities between efforts to infiltrate Democratic and Republican networks during the race between Hillary Clinton and Mr Trump.
The officials also reportedly said the US intercepted communications in which Russian officials celebrated Mr Trump's victory.
Mr Trump has repeatedly cast doubt on intelligence claims of Russian hacking in the presidential election on Twitter.
Mr Trump was due to be briefed on the intelligence on Friday by the Director of National Intelligence James Clapper, CIA Director John Brennan and FBI Director James Comey.
Mr Biden condemned Barack Obama's successor in an interview with US network PBS and in a message to Mr Trump said: "Time to be an adult, you're president."
When asked what he thought of Mr Trump's regular attacks on the Obama administration on Twitter, Mr Biden said: "Grow up Donald, grow up, time to be an adult, you're president. Time to do something. Show us what you have."
He also said it was "dangerous" for a president-elect to publicly criticise the intelligence agencies.
Mr Biden said the report by US intelligence agencies outlined the extent of Russian attempts "as a matter of policy" to "affect and ... discredit the US electoral process" in the build-up to the election.
He said the hacking was part of a campaign to undermine Mrs Clinton.
Mr Trump later tweeted that his rival's campaign had been unable to compete with the passion of his voters.
America's top spy chief said he is "more resolute" than ever before that Russia directly interfered.
Russia has denied involvement after the US announced sanctions against Russian officials.
Amid the criticism, Mr Trump is expected to select former senator Dan Coats to lead the Office of the Director of National Intelligence.
Mr Trump's transition team has played down the prospect of him making sweeping changes to key roles within the intelligence community.
He has seen a notable change within his team as former CIA director James Woolsey has stepped aside as a senior adviser to the president-elect.
Woolsey is understood to have played a diminished role in the Trump team's discussions on intelligence matters and became uncomfortable about being labeled as an adviser.