 -- Former Director of National Intelligence James Clapper denied on Monday that there were any wiretaps on Trump Tower during the 2016 campaign, and also revealed that the president-elect had asked him to publicly disavow a private investigator's un-corroborated dossier on Trump circulating among journalists.

Clapper was responding today to a weekend tweet tirade by the President, who made unsubstantiated claims that former President Barack Obama had ordered a wiretap of Trump Tower during the election campaign.

"There was no wiretap against Trump Tower during the campaign conducted by any part of the National Intelligence Community," Clapper, America's top spy until January 20, told ABC News' Brian Ross in an interview in Washington, D.C., “none at all...including the FBI”.

Clapper was encouraged by FBI leaders over the weekend to speak out after Trump essentially accused the Bureau of wiretapping the Trump campaign on Obama’s orders, current and former officials said.

The only federal wiretapping inside the U.S. allowed under the law in national security or criminal investigations is done by the FBI, “and if there was one [a wiretap], it was awfully secret," Clapper added.

The retired three-star general and career intelligence officer also revealed for the first time that days after briefing the President-Elect in Trump Tower on Jan. 6 about Russian attempts to influence the U.S. 2016 election, Trump in a phone call asked Clapper to rebut a dossier compiled by a British former MI-6 spy, Christopher Steele, for a Washington private intelligence firm which gathered derogatory information for Trump political opponents.

Details of the dossier had begun to leak out after the Jan. 6 briefing, in which FBI Director James Comey informed Trump of the file’s existence as a warning that the Kremlin might try to use it.

“His main concern was, I think he asked me to put out a rebuttal or repudiation of the dossier which I couldn't do and didn't,” Clapper told ABC News in the interview on Monday. “I had no way of validating, at the time corroborating the information in it. Some of the second and third order sources that were used in that we could not corroborate and I told him that.”

Instead, Clapper released a statement on Jan. 11 which fell far short of what Trump had asked for, according to a senior official who confirmed Clapper’s story. The Clapper statement in January said only that he told the president-elect, “This document [the Steele dossier] is not a U.S. Intelligence Community product and that I do not believe the leaks came from within the IC."

Trump has often taken to Twitter to communicate his opinions directly to the public, and early on Saturday morning he tweeted accusations – without offering evidence – that Obama spied on him during the campaign, writing: "Just found out that Obama had my 'wires tapped' in Trump Tower just before the victory. Nothing found."

Clapper, a career military and intelligence officer who served presidents of both political parties, told ABC News that President Obama could not and did not order such surveillance.

"Not President Obama, he did not, could not, that's not how it's done. It has to be done through a court, and he would not." he said. "And certainly during the six and a half years that I was DNI, neither he nor anyone else in the White House ever asked for any sort of this, surveillance such as this."

Clapper said he was curious what the basis for the allegation was, saying the Trump could have found that out for himself with one phone call. “I think the Department of Justice probably could clear this up in a heartbeat," Clapper said.

A spokesman for former President Obama quickly issued a strong denial to the claim on Saturday.

"A cardinal rule of the Obama administration was that no White House official ever interfered with any independent investigation led by the Department of Justice," Obama spokesman Kevin Lewis said. "As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any U.S. citizen. Any suggestion otherwise is simply false."

Speaking of the president's unsubstantiated wiretap allegations, Clapper said: "I think it's a terrible distraction, and it gets us away from some of the, in my mind, more crucial issues. You know the last one I dealt with, significant one I dealt with, was the Russian interference in our election, which I thought, both as my position as DNI and as a citizen, was a terrible thing, and I wish we could clear the air on that and deal with that."

On Sunday, government sources familiar with FBI Director James Comey's thinking told ABC News that the director asked the Justice Department to publicly refute the president's assertions made on Twitter.

The FBI director was said to be concerned that the tweets – which he believed to be inaccurate – had created the impression of improper conduct on the part of the FBI, according to sources.

The FBI and Department of Justice have not commented.

Asked on Monday by ABC News' George Stephanopoulos on "Good Morning America" whether President Trump accepted the FBI director's reported denial of his wiretap claim, White House spokesperson Sarah Huckabee Sanders said, "you know, I don't think he does, George."

ABC News' Rhonda Schwartz, Randy Kreider, Paul Blake, Alex Hosenball, Cho Park, Taylor Harris and Laura Sanicola contributed to this report.