A powerful commander of Iran's elite Revolutionary Guards said Donald Trump should address any threats against Tehran directly to him.
He also mocked the US president for using the language of "night clubs and gambling halls".
The comments by Major-General Qassem Soleimani were the latest salvo in a war of words between the two countries.
"As a soldier, it is my duty to respond to your threats ... If you wants to use the language of threat ... talk to me, not to the president [Hassan Rouhani]. It is not in our president's dignity to respond to you," Mr Soleimani was quoted as saying by Iran's semi-official Tasnim news agency.
Mr Soleimani's message was in essence a warning to the United states to stop threatening Iran with war or risk exposing itself to an Iranian response.
"We are near you, where you can't even imagine... Come. We are ready ... If you begin the war, we will end the war," Mr Soleimani was quoted as saying. "You know that this war will destroy all that you possess."
Israel's Energy Minister Yuval Steinitz said the fiery rhetoric of Mr Soleimani was only "empty talk" because Iran was aware of "the strength and might of the US military".
Last week, Mr Trump said in a tweet directed at Mr Rouhani: "Never, ever threaten the United States again or you will suffer consequences the likes of which few throughout history have ever suffered before. We are no longer a country that will stand for your demented words of violence & death. Be cautious!"
A few hours earlier, Mr Rouhani had addressed Mr Trump in a speech, saying that hostile US policies could lead to "the mother of all wars".
Fanning the heightened tensions, US national security adviser John Bolton followed with a statement: "President Trump told me that if Iran does anything at all to the negative, they will pay a price like few countries have ever paid before."
Mr Bolton is a proponent of interventionist foreign policy and was US ambassador to the United Nations in the administration of George W. Bush during the Iraq war.
"You [Trump] threaten us with paying a price like few countries have ever paid. Trump, this is the language of night clubs and gambling halls," Mr Soleimani said.
Iran's Guards commanders have threatened to destroy US military bases across the Middle East and target Israel, which Iran refuses to recognise, within minutes of being attacked.
Since Mr Trump's decision in May to withdraw the United States from a 2015 nuclear agreement between Iran and world powers, Tehran's clerical establishment has been under increasing US pressure and the prospect of possible sanctions.
- Reuters