US President Donald Trump called Iran the "number one terrorist nation" in the world and again refused to rule out military action against the Islamic Republic.
Speaking on Wednesday during a state visit to the United Kingdom, Trump said there was a possibility his administration would need to launch an offensive on Iran.
"Do I want to? No. I'd rather not. But there's always a chance," he told British television station ITV. "I would much rather talk."
Friction between the United States and Iran has escalated in recent weeks after more than a year of increasingly fractious relations unleashed by Trump's decision in May 2017 to withdraw from a landmark nuclear deal.
Under the 2015 agreement, Iran agreed to scale back its nuclear programme in exchange for the lifting of economic sanctions.
Iran vows 'resistance'
Since pulling out of the nuclear deal, the White House has rolled out a "maximum pressure" policy against Iran. As part of that, Trump's administration reimposed punitive sanctions and moved to cut the country's oil exports to zero, sending its economy into freefall.
The US also blacklisted Iran's Revolutionary Guard Corps as a "terrorist group", which prompted a tit-for-tat response from Tehran. Last month, Washington bolstered its military presence in the Gulf in response to an unspecified threat.
Since then, a war of words between the arch-rivals has continued to escalate.
"So Iran is a place that was extremely hostile when I first came into office," Trump said in the interview. "They were a terrorist nation - number one in the world at that time - and probably maybe are today."
Iran's Supreme Leader Ayatollah Ali Khamenei said on Tuesday that Tehran would continue "resisting" US economic and political pressure.
"Standing and resisting the enemy's excessive demands and bullying is the only way to stop him," Khamenei said in a speech broadcast on state television during an event in the Iranian capital to mark the 30th anniversary of the death of Grand Ayatollah Ruhollah Khomeini.
Iran has rolled back some of its commitments under the nuclear deal and threatened to turn its back on more of the accord if it does not receive sanctions relief.
It has also refused to meet US officials for negotiations until Washington returns to the agreement.
The Vienna-based International Atomic Energy Agency has repeatedly confirmed Iran's compliance with the nuclear deal, including during its most recent quarterly report published last week.
