President Donald Trump said Friday he did not give final approval for a set of airstrikes on Iranian targets he earlier said he called off over concerns the death toll that would have been disproportionate to Iran's downing of a U.S. drone.

Trump said in an interview with NBC News that no planes had been deployed when he decided to halt the attacks, but said "they would have been pretty soon" if he had not called them off.

"Things would have happened to a point where you would not turn back, or couldn't turn back," he said. "Nothing was green lighted until the very end because things change."

Trump earlier Friday tweeted the U.S. was "cocked & loaded" to strike three Iranian sites within 10 minutes of the operation being carried out.

"I thought about it for a second and I said, you know what, they shot down an unmanned drone, plane, whatever you want to call it, and here we are sitting with 150 dead people that would have taken place probably within a half an hour after I said go ahead," Trump then told NBC News. "And I didn't like it, I didn't think, I didn't think it was proportionate."

The Federal Aviation Administration issued a notice late Thursday prohibiting U.S. airliners from flying over parts of Iran-controlled airspace after Trump vowed the public would "find out" what the U.S. response would be to the downing of the American drone.

Tensions have been rising between the U.S. and Iran since May 2018 when Washington unilaterally withdrew from a landmark 2015 nuclear deal between Tehran and the five permanent members of the UN Security Council plus Germany and the EU.

The U.S. has since embarked upon a diplomatic and economic campaign to ramp up pressure on Iran to force it to renegotiate the agreement.

Part of its campaign has included the re-imposition of U.S. sanctions on exports of Iranian crude oil, which has sent the Iranian economy into a nosedive.

The U.S. has also increased its military presence in the Middle East, deploying a carrier strike force, bomber task force and Patriot missile battery and using threats from Iran as justification for the actions.

On Monday, the Trump administration announced it would