Trump's willingness to disregard the intelligence community's "overwhelming evidence" was "extraordinarily damaging,"
"I don't believe it," Trump said in a pre-recorded interview that was broadcast Sunday on Fox News.
"I think it's ridiculous," Trump said, putting it down as an attempt by Democrats to find an excuse for their embarrassing election loss.
In the interview Trump touched on other issues -- questioning US commitment to the "one China policy" without concessions from Beijing, and hailing Exxon CEO Rex Tillerson, who is under consideration for secretary of state, as "a world class player."
But the controversy over the latest US intelligence consensus on Russia and Trump's skepticism of the findings dominated the conversation at a time of deepening political divisions over how to respond to the hacking attacks.
Two top Republican senators -- John McCain and Lindsey Graham -- joined leading Democrats Sunday in calling for greater public disclosure about "recent cyber attacks that have cut to the heart of our free society."
"This cannot become a partisan issue. The stakes are too high for our country," they said in a joint statement with Chuck Schumer, the incoming Democratic leader in the Senate, and Jack Reed, the ranking Democrat on the Senate Armed Services Committee.
They pledged to work across party lines to have the incidents investigated, but other Republicans said the evidence does not support the conclusions that the Russian meddling was aimed at helping Trump.
Adam Schiff, the ranking Democrat on the House Intelligence Committee, said the hacking was definitely the work of the Russians.
"This was not China. This wasn't a 400-pound guy in New Jersey or anyone else," Schiff said, mocking similar comments Trump has made. "This was the Russians."
Trump's willingness to disregard the intelligence community's "overwhelming evidence" was "extraordinarily damaging," he said.
US intelligence has previously linked Russia to leaks of damaging emails from Democratic candidate Hillary Clinton's campaign but saw it as a broad bid to undermine confidence in the US political process.
On Friday, however, the Washington Post reported that the CIA has since concluded that the aim of the cyber intrusions was to help Trump win the election.
The New York Times quoted senior administration officials as saying there was "high confidence" that the Russians hacked both the Democratic and Republican National Committees, but leaked only documents damaging to Clinton through WikiLeaks.
Reince Priebus, the Republican National Committee chairman and Trump's incoming White House chief of staff, said the FBI had investigated and told the RNC it had not been hacked.
WikiLeaks founder Julian Assange has denied links with Russia's government.
Trump dismissed the intelligence reports, asserting there is "great confusion" over the issue within the spy agencies.
"Nobody really knows," he said. "They have no idea if it's Russia or China or somebody. It could be somebody sitting in a bed some place. They have no idea."
Trump suggested he had little confidence in the US intelligence agencies and would clean house once in office.
"We're going to have different people coming in because we have our people, they have their people."
Trump has kept the US intelligence community at arm's length since his election, pointedly eschewing their daily briefing on world threats.
"I get it when I need it," he said.
"You know, I'm a smart person. I don't have to be told the same thing and the same words every single day for the next eight years."
Moscow's motives have drawn attention in part because Trump has often praised Russian President Vladimir Putin as a strong leader, ignoring his actions in Ukraine and Syria.
Trump, who is expected to name a secretary of state this week, is reported to have settled on Rex Tillerson, the Exxon chief, as his top choice.
Tillerson's close ties to Putin have raised concerns among some lawmakers, but Trump sees the oil executive's Russian dealings as a plus.
"In his case, he's much more than a business executive. He's a world class player," Trump said of the 64-year-old Texan, who has run Exxon since 2006.
"To me, a great advantage is he knows many of the players. And he knows them well. He does massive deals in Russia. He does massive deals for the company, not for himself," he said.
McCain expressed concern that Tillerson was too close to Putin, and told CBS' Face the Nation that the deals they have done together "would color his approach to Vladimir Putin and the Russian threat."
On China, Trump touched a raw nerve by questioning whether the United States should continue its "one China policy" without concessions from Beijing on trade and other issues, threatening to upend decades of Sino-American diplomacy.
"I don't want China dictating to me," Trump said as he made a vehement defense of his recent phone conversation with the president of Taiwan.
"I don't know why we have to be bound by a one China policy unless we make a deal with China having to do with other things, including trade," he added.
He was responding to a question about taking a call earlier this month from Tsai Ing-wen, the leader of Taiwan, a self-ruling island that Beijing considers a rogue province awaiting unification.
It was a break from decades of US diplomatic tradition that recognizes Beijing as the sole representative of China, an understanding that has been a cornerstone of the relationship between the countries since Richard Nixon went to China in 1972.