U.S. officials expressed hope – and some optimism – Sunday that the escalation of tensions with Iran could be resolved without military conflict, though they said actions by leaders in Tehran would determine what happens next.

President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE said in an interview that aired Sunday on "Meet the Press" that he was not looking for war and he would meet with Iranian officials without preconditions.

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“I'm not looking for war and if there is, it'll be obliteration like you've never seen before. But I'm not looking to do that. But you can't have a nuclear weapon. You want to talk? Good,” Trump said.

Asked if talks would include preconditions, Trump said “not as far as I'm concerned. No preconditions.”

He added that he believes Iran wants to negotiate.

"And I think they want to make a deal. And my deal is nuclear. Look, they’re not going to have a nuclear weapon," he said. "I don’t think they like the position they’re in. Their economy is, is absolutely broken.”

This came after Trump said he almost launched a retaliatory strike over Iran shooting down an unmanned U.S. drone last week. In a tweet he said he called off the attack after learning the number of potential casualties.

He added that the strike will not go forward "at this time."

Appearing on CNN's "State of the Union," on Sunday Vice President Mike Pence Michael (Mike) Richard PencePence vows for law and order everywhere Trump met with chants of protest as he pays respects to Ruth Bader Ginsburg The Hill's 12:30 Report: Ginsburg lies in repose MORE also expressed optimism on Iran, saying that the U.S. is still not sure whether the drone's downing was authorized by Iranian leadership.

“The president … had doubt as to whether the downing of our unmanned aircraft was authorized at the highest levels,” Pence said. “We’re not convinced it was authorized at the highest levels.”

He also reiterated President Trump's message about cancelling the planned strike.

“This is a president who’s always going to count the cost,” he said. “The president looked at the potential loss of human life and concluded that was not proportionate.”

Rep. Mac Thornberry William (Mac) McClellan ThornberryTrump payroll-tax deferral for federal workers sparks backlash Overnight Defense: Woodward book causes new firestorm | Book says Trump lashed out at generals, told Woodward about secret weapons system | US withdrawing thousands of troops from Iraq Top Armed Services Republican 'dismayed' at Trump comments on military leaders MORE (R-Texas), when asked by Martha Raddatz on ABC's "This Week" whether cyberattacks and sanctions were enough retaliation, said, "That's going to really depend on the Iranians. This story is not over. And the question is how do they respond to this relatively restrained response by President Trump."

Sen. Tom Cotton Tom Bryant CottonThe Hill's 12:30 Report: Trump stokes fears over November election outcome The Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Abortion stirs GOP tensions in Supreme Court fight MORE (R-Ark.) broke with the president, doubling down on his call for a retaliatory military strike, which he first called for after the U.S. blamed Iran for attacks on two oil tankers in the Gulf of Oman.

"I fear if Iran doesn't have firm set of boundaries drawn around its behavior, we're going to see an attack on U.S. ship or a U.S. manned aircraft," he said in a "Fox News Sunday" appearance.

He added that he hopes Trump's statement that the U.S won't tolerate attacks on Americans l "gets through to the leaders in Tehran."

A former top military official in the George W. Bush and Obama administrations, however, warned that a move against Iran could "spin out of control" in an appearance on ABC's "This Week."

"The last thing in the world we need right now is a war with Iran," said former Joint Chiefs of Staff Chairman Mike Mullen.

"I think the politicians need to figure out a way to achieve the objective, which is Iran without a nuclear weapon, without -- from my perspective -- without regime change, without going to war," he said.

Tensions between Washington and Tehran have been increasing for months. Last week, President Trump announced new sanctions on Iran and U.S. cyber forces reportedly struck Iranian military computer systems.