The White House has blamed Iranian president Hassan Rouhani for inciting a war of words with US leader Donald Trump, who warned that verbal threats could escalate into military conflict with America.

Mr Trump, who campaigned on a promise to bring a more hawkish approach to Iran, sent an all-caps tweet late on Sunday warning of dire consequences for the longtime foe of the US.

“NEVER EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKE OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE”, he wrote.

The US leader was responding to Mr Rouhani, who had remarked earlier in the day that “America must understand well that peace with Iran is the mother of all peace and war with Iran is the mother of all wars”.

Within hours, Iran’s state-owned news agency IRNA dismissed Mr Trump’s tweet, describing it as a “passive reaction” to Mr Rouhani’s remarks.

US Iran
(PA Graphics)

On Monday, the White House said the US president’s tweet shows he is not going to tolerate critical rhetoric from Iran and insisted Mr Trump is not escalating tensions between the two countries.

“If anybody’s inciting anything, look no further than to Iran,” press secretary Sarah Sanders said, adding that Mr Trump has been “very clear about what he’s not going to allow to take place”.

In Tehran, a headline on a local newspaper quoted Mr Rouhani as saying: “Mr Trump, do not play with the lion’s tail.”

Prominent Iranian analyst Seed Leilaz downplayed the war of words, describing it as “the storm before the calm”.

Mr Leilaz said he was not “worried about the remarks and tweets”, and that “neither Iran, nor any other country is interested in escalating tensions in the region”.

US Iran
(PA Graphics)

Citing harsh words the United States and North Korea had exchanged before the high-profile summit between Mr Trump and North Korean leader Kim Jong Un, Mr Leilaz said Mr Trump and Mr Kim got “closer” despite the warring words.

The US president’s eruption on Twitter came after a week of heavy controversy about Russian meddling in the 2016 US election, following the Helsinki summit with Russian leader Vladimir Putin.

The tweet is reverberating across the Middle East.

Israeli prime minister Benjamin Netanyahu praised the US president’s “strong stance” after years in which the Iranian regime was “pampered by world powers”.

Mr Trump earlier this year pulled the US out of the international deal meant to prevent Tehran from developing a nuclear weapon and ordered increased American sanctions, as well as threatening penalties for companies from other countries that continue to do business with Iran.

A street scene in Tehran
Iranians have largely shrugged off the possibility of military conflict following the war of words (AP)

With the economic pressure, Mr Trump said earlier this month that “at a certain point they’re going to call me and say ‘let’s make a deal,’ and we’ll make a deal”.

Iran has rejected talks with the US, and Mr Rouhani has accused the US of stoking an “economic war”.

Mr Rouhani also suggested Iran could immediately ramp up its production of uranium in response to US. pressure.

That could potentially escalate the very situation the nuclear deal sought to avoid — an Iran with a stockpile of enriched uranium that could lead to making atomic bombs.

Mr Trump’s tweet suggested he has little patience with the trading of hostile messages with Iran, using exceptionally strong language and writing in all capitals.

He wrote: “WE ARE NO LONGER A COUNTRY THAT WILL STAND FOR YOUR DEMENTED WORDS OF VIOLENCE & DEATH. BE CAUTIOUS!”