Salehi, Head of the Atomic Energy Organization of Iran (IAEA), told reporters that if the US pulls out of the Joint Comprehensive Plan of Action (JCPOA), Tehran is ready to respond with a number of options, including those that involve promptly resuming its nuclear activities.
The Islamic Republic is capable to resume enriching uranium to the 20-percent level in four days in case the withdrawal takes place, he said.
"We hope that the other side makes a wise decision and avoids carrying out an action that would cause a nuisance for itself and others," Salehi said, as reported by Press TV.
He pointed out that Iran has repeatedly expressed hope that circumstances would never make it take "technical decisions" but stressed that "once the [Islamic] establishment decides, we are ready like an army to take action."
The Iranian nuclear chief also cautioned Europe against blindly following Washington's policies, saying that it would mean "Europe is not an independent body and is a satellite in the US political orbit."
His remarks came after about 500 British, French and German MPs sent a letter to the US Congress, in which they said that scrapping the Iran nuclear deal would damage the mechanism of control on the Iranian nuclear program and may add to new tensions in the Middle East.
In January, the US President announced the extension of sanctions relief for Iran, given that the Islamic Republic was in line with the obligations set by the nuclear deal, inked by Brussels, Tehran and the P5+1 group of nations, including Russia, the US, China, France and the UK plus Germany, on July 14, 2015.
He said that it would be the last time he signed the sanctions waiver unless the European allies agree to a supplemental deal to fix the "terrible flaws" of the JCPOA, according to Trump, who also slammed Iran's missile program.
Other JCPOA signatories, including Russia, China, Britain, Germany and France, criticized Trump's stance, saying that the Iran nuclear deal is working successfully.