Iranian officials told Reuters on Friday that Tehran had received a message from US President Donald Trump through Oman overnight warning that a US attack on Iran was imminent.

They spoke shortly after the New York Times reported that Trump had approved military strikes against Iran on Friday in retaliation for the downing of a US surveillance drone, but called off the attacks at the last minute.

"In his message, Trump said he was against any war with Iran and wanted to talk to Tehran about various issues...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," one of the officials told Reuters, speaking on condition of anonymity.

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."

After weeks of rising tension amid a spate of attacks on oil tankers in the Gulf, Iran said on Thursday it had shot down an unmanned US military surveillance drone, fanning fears of an overt military confrontation between the longtime adversaries.

The New Times quoted a senior administration official as saying, US warplanes took to the air and ships were put in position for a retaliatory attack only for an order to come to stand down, without any weapons being fired.

Targets had included Iranian radar and missile batteries, the paper cited senior administration officials involved in, or briefed on, the deliberations, as saying.

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

It was unclear if attacks on Iran might go ahead later, it added, nor was it known whether Trump had changed his mind or whether his administration had become concerned about logistics or strategy.

- Reuters