File photo: US President Donald Trump. Photograph:( Reuters )
Trump, who was speaking to reporters at the White House, made his comments after recently calling off military action against Iran to retaliate for the downing of a US military drone.
US President Donald Trump said Saturday he will impose additional sanctions on Iran in an effort to prevent Tehran from obtaining nuclear weapons, adding that military action was still a possibility.
"We are putting additional sanctions on Iran," Trump said. "In some cases we are going slowly, but in other cases we are moving rapidly."
The president said military action "is always on the table" against Iran.
But Trump also indicated he was open to reversing the escalation, adding he was willing to quickly reach a deal with Iran that he said would bolster the country's flagging economy.
"We will call it 'Let's make Iran great again.'"
Trump spoke to reporters as he prepared to depart Washington for the presidential retreat Camp David, where he said he would be deliberating on Iran.
Watch: Trump says, 'not looking for war with Iran'
Iran said on Saturday it would respond firmly to any US threat, the semi-official Tasnim news agency reported, amid escalating tension between Tehran and Washington over the shooting down of an unmanned US drone by the Islamic Republic.
On Thursday, an Iranian missile destroyed a US Global Hawk surveillance drone. Tehran repeated on Saturday that the drone was shot down over its territory. Washington said the incident had occurred in international airspace.
US President Donald Trump said on Friday he aborted a military strike to retaliate because it could have killed 150 people, and signalled he was open to talks with Tehran.
"Regardless of any decision they (US officials) make ... we will not allow any of Iran's borders to be violated. Iran will firmly confront any aggression or threat by America," Foreign Ministry spokesman Abbas Mousavi told Tasnim.
Worries about a confrontation between Iran and the United States have mounted despite Trump saying that he has no appetite to go to war with Iran. Tehran has also said it is not seeking a war but has warned of a "crushing" response if attacked.
"Any mistake by Iran's enemies, in particular America and its regional allies, would be like firing at a powder keg that will burn America, its interests and its allies to the ground," the senior spokesman of Iran's Armed Forces, Abolfazl Shekarchi, told Tasnim on Saturday.
A senior commander of the elite Revolutionary Guards struck a similarly defiant note, in comments quoted by the Islamic Republic News Agency (IRNA).
"This is our response to a violation of Iranian space and if the violation is repeated then our response will be repeated," said Brigadier General Amirali Hajizadeh, head of the Guards' aerospace division.
"It's possible that this infringement of the Americans was carried out by a general or some operators."
Iran's Foreign Ministry summoned a diplomatic representative of the United Arab Emirates on Saturday because the UAE allowed the drone that was shot down to be launched from a US military base on its territory, the Fars news agency reported.