The United Nations voiced concern on Monday about the rising rhetoric between the United States and Iran and called on the two sides to dial down their remarks.

The appeal came after President Donald Trump on Sunday warned that any attack from Iran would be met with a devastating US response that would mean “the official end of Iran.”

“We are concerned about the rising rhetoric,” said UN spokesman Stephane Dujarric, who cited the firing of a rocket on Sunday, which struck a Baghdad area that houses foreign embassies including that of the US, as being “also a concern.”

“We would ask all parties to lower the rhetoric and lower the threshold of action as well,” said the spokesman.

UN officials are holding contacts with the US and Iran at various levels to try to calm the situation, said Dujarric, but he did not provide details of those talks.

Relations between Washington and Tehran plummeted a year ago when Trump pulled out of a landmark 2015 nuclear deal with Iran and imposed tough sanctions.

Tensions have risen this month after Washington announced more economic measures against Tehran, before deploying a carrier group and B-52 bombers to the Gulf over alleged Iranian “threats.”

The Trump administration last week ordered non-essential diplomatic staff out of Iraq, citing the danger posed by Iranian-backed Iraqi armed groups.

Iranian Foreign Minister Mohammad Javad Zarif responded to Trump's tweet on Monday, describing it as “genocidal taunts” and adding: “Never threaten an Iranian. Try respect — it works!