Iran has been accused of "destabilizing activity" after it test-fired a nuclear ballistic missile over the weekend.
The US claims the missile launch was in defiance of a UN Security Council resolution that called on Iran not to undertake any activity designed to be capable of delivering nuclear weapons.
Iran tested a nuclear ballistic missile over the weekend
Now Washington has lashed out at President Hassan Rouhani and his country, blasting them for totally disregarding the deal.
President Donald Trump's national security adviser Michael Flyn told a White House briefing: "As of today, we are officially putting Iran on notice."
The test took place at a test site near Semnan
The last time a weapon was fired was in July 2016
He also said the firing demonstrated that it is "emboldened" by the controversial nuclear agreement, rather than "thankful" for the deal.
The retired US Army lieutenant general added the Trump administration was taking a stand over the launch "that puts American lives at risk."
But it is unknown what the miitary boss means by the term "on notice".
White House press secretary Sean Spicer later added that the administration "wanted to make very clear that we felt that [Iran's] actions are both provocative and in violation [of the nuclear deal] and make sure they knew that were not going to sit by and do nothing.
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Both Trump and Flynn have been vocal opponents of an international deal that saw Iran curb its nuclear programme in return for sanctions relief.
In his first public remarks since taking office, National Security Adviser Michael Flynn accused former president Barack Obama's administration of having "failed to respond adequately to Tehran's malign actions".
A US official confirmed the deadly missile exploded 630 miles away from where it was fired, claiming the Iranians were "testing Trump".
The test took place at a test site near Semnan, according to the official who would only speak on condition of anonymity.
Iran is banned from any activity designed to be capable of delivering nuclear weapons
A US official confirmed the deadly missile exploded 630 miles away
Instead of being thankful to the United States for these agreements, Iran is now feeling emboldened
Trump's national security adviser Michael Flyn
The last time this missile was launched was July 2016, meaning this latest detonation could well be in response to Trump's executive order slamming shut the borders to anyone coming from Syria, Iran, Iraq, Yemen, Somalia, Sudan and Libya.
Earlier, Iranian defence minister Hossein Dehghan confirmed a medium-range ballistic missile was launched and exploded after travelling 630 miles.
However, he said the test did not violate a UN Security Council resolution that bans Iran from developing missiles.
He added: "We will not allow foreigners to interfere in our defence affairs".
Mr Flynn said Tehran had defied the resolution and hit out at Iran's "destabilising behaviour across the Middle East".
He said: "President Trump has severely criticised the various agreements reached between Iran and the Obama Administration, as well as the United Nations – as being weak and ineffective.
"Instead of being thankful to the United States for these agreements, Iran is now feeling emboldened."
While the new US ambassador to the United Nations Nikki Haley called the test "unacceptable".
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The row comes amid a 90-day US ban on visas for migrants or visitors from Iran, as well as six other Muslim-majority countries.
Tehran said it will take "proportionate legal, consular and political action" while President Rouhani warned Mr Trump "will cost the US a lot until he learns what is happening in the world".
He said: "(Mr Trump) is new to politics. He has been in a different world. It's a totally new environment to him."