Donald Trump reportedly gave initial approval for the US military to launch strikes on Iran in retaliation for Tehran shooting down an American drone, before pulling back at the last minute.

Planes were in the air and ships were in position, but no missiles had been fired when word came to stand down on Thursday night, the New York Times quoted an unnamed official as saying.

US military and diplomatic officials were expecting strikes on a handful of radar and missile sites after the president’s top national security officials and congressional leaders gathered at the White House, the paper said. The military operation was called off around 7.30pm ET (12.30am BST).

The UK was informed of the US plan for the attack and not told the reprisal raids were off until 3am UK time (10pm ET).

It was not clear whether strikes would go ahead at a later date. The White House and Pentagon have not commented on the reports.

On Friday Reuters reported that Trump had passed a message to Tehran via Oman warning an attack on Iran was imminent.

“In his message, Trump said he was against any war with Iran and wanted to talk to Tehran about various issues,” an anonymous Iranian official told the news agency. “He gave a short period of time to get our response but Iran’s immediate response was that it is up to Supreme Leader [Ayatollah Ali] Khamenei to decide about this issue.”

A second Iranian official said: “We made it clear that the leader is against any talks, but the message will be conveyed to him to make a decision ... However, we told the Omani official that any attack against Iran will have regional and international consequences.”

Oman – along with Japan, Iraq and to a lesser extent Switzerland – has acted as an intermediary for messages between Trump and the Iranian leadership.

Khamenei has repeatedly said he will not talk to the US until it lifts economic sanctions, adding he does not trust Trump’s motives.

The reported contact with Oman suggests that the White House might have been involved in brinkmanship with Tehran, but pulled back when Iran did not flinch.

US officials said that Trump was known to want talks, but was also a believer in sending mixed messages to keep his adversaries guessing about his next move.

He is surrounded by some officials – notably the national security adviser, John Bolton – who are thought to favour an attack.

The Democratic House speaker, Nancy Pelosi, who had attended a classified White House briefing with other congressional leaders on Thursday, had said the administration should “do everything in our power to de-escalate”, while the Senate Democratic leader, Chuck Schumer, said he worried the administration “may bumble into a war”.

He said he told the president there must be a “robust, open debate” and Congress should have a real say. Adam Schiff, the chairman of the House intelligence committee, said: “The president certainly listened to what we had to say.”

One of the targets of the planned strikes was the S-125 Neva/Pechora surface-to-air missile system, Newsweek quoted a Pentagon official as saying. It reported that the US believed the system was behind the US drone attack, although Tehran said it had used its “3rd Khordad” air defence system, the Iranian equivalent of the Russian Buk system that downed Malaysia Airlines flight MH17 over Ukraine in 2014.

The strikes were seemingly set for early in the day to minimise risk to the Iranian military or to civilians.

Trump had earlier appeared keen to calm tensions following the shooting down early on Thursday of the US Global Hawk drone, saying blame might be on a “loose and stupid” Iranian officer acting without authorisation from Tehran.

Many observers fear there is an absence of ways out if warfare was to break out.

Trump’s allies claimed he was intent on listening to all sides of the argument, but his instinct, relayed to the UK, had been to use economic pressure to force the Iranians to the bargaining table, and not to press for regime change.

“We didn’t have a man or woman in the drone. It would have made a big, big difference,” Trump said. Asked how the US would respond, he said: “You’ll find out.”

The downing on Thursday of the unarmed aircraft was the latest of a series of incidents that have raised tensions in the Gulf region. Earlier, a total of six oil tankers were damaged in two separate attacks.

According to a US official who spoke to the Associated Press, the strikes were recommended by the Pentagon and were among the options presented to senior administration officials.

The report of the swift reversal on US retaliation came as the US Federal Aviation Administration banned all US airlines and aircraft from flying in Iranian airspace close to where the US drone was shot down due to “heightened military activities” in the region.

There have been reports of an increase in Iran Revolutionary Guards Corps activity in the strait of Hormuz, increasing the chances of attacks on oil tankers operated by America or its Gulf allies if the US did mount an attack.

The FAA issued an emergency order saying all flight operations over water in the Tehran flight information region of the Persian Gulf and Gulf of Oman were prohibited until further notice because military activities and political tensions “present an inadvertent risk to US civil aviation operations and potential for miscalculation or mis-identification”.

The order applies to US aircraft only but since the MH17 disaster all countries rely on airspace risk advice from the US, UK, France and Germany.

On Thursday, Iran’s foreign minister and the US military offered competing graphics showing the drone’s flight path and where it was brought down.

Javad Zarif said Iran had recovered parts of the drone in its waters and that it had originally taken off from the United Arab Emirates.

A map issued by US Central Command suggested the drone was brought down in international waters in the strait of Hormuz.

Flight tracking data showed commercial aircraft flying close to the Global Hawk drone at the time it was shot down, said OPS Group, which provides safety guidance to air operators.

“The threat of a civil aircraft shootdown in southern Iran is real,” it advised operators on Thursday. “Avoiding the strait of Hormuz area is recommended – misidentification of aircraft is possible.”

Last month, the FAA advised airlines to exercise caution in flying over Iran and nearby areas, due to heightened military activities and increased political tension.

It said: “Although Iran likely has no intention to target civil aircraft, the presence of multiple long-range, advanced anti-aircraft capable weapons in a tense environment poses a possible risk of miscalculation or misidentification, especially during periods of heightened political tension and rhetoric.”

On Friday Sardar Amir Ali Hajizadeh, a commander in Iran’s air force, claimed: “We could have targetted a US-35 P-8 American plane … But we did not do this because our goal was to bring the US drone down and to warn off the terrorist forces of the US regime.” There was no independent verification for his claim.