Ebrahim Zolfaqari, spokesperson for Iran's Khatam al-Anbiya central military headquarters, said the US should expect heavy consequences for its actions.
"Mr Trump, the gambler, you may start this war, but we will be the ones to end it," Zolfaqari said in English at the end of a recorded video statement.
Iran and Israel traded air and missile strikes as the world braced for Tehran's response to the US attack on its nuclear sites over the weekend, which Trump suggested could lead to the overthrow of the Iranian government.
"It's not politically correct to use the term, "Regime Change," but if the current Iranian Regime is unable to MAKE IRAN GREAT AGAIN, why wouldn't there be a Regime change??? MIGA!!!" Trump wrote on Truth Social.
Commercial satellite imagery indicated Saturday's attack on Iran's Fordow nuclear plant far underground had severely damaged or destroyed the site and the uranium-enriching centrifuges it housed, but its status remained unconfirmed, experts said.
In his latest social media comments on the US strikes, Trump said: "Monumental Damage was done to all Nuclear sites in Iran."
"The biggest damage took place far below ground level. Bullseye!!!" he wrote on his Truth Social platform.
Trump earlier called on Iran to forgo any retaliation and said the government "must now make peace" or future attacks would be "far greater and a lot easier", fuelling global concern about further escalation of conflict in the Middle East.
The US launched 75 precision-guided munitions including bunker-buster bombs and more than two dozen Tomahawk missiles against three Iranian nuclear sites, the chairman of the Joint Chiefs of Staff, General Dan Caine, told reporters.
The UN nuclear watchdog, the International Atomic Energy Agency, said no increases in off-site radiation levels had been reported after the US strikes. Rafael Grossi, the agency's director general, told CNN that it was not yet possible to assess the damage done underground.
A senior Iranian source told Reuters that most of the highly enriched uranium at Fordo had been moved elsewhere before the attack. Reuters could not immediately corroborate the claim.
Tehran, which denies its nuclear program is for anything other than peaceful purposes, launched a volley of missiles towards Israel in the aftermath of the US attack, wounding scores of people and destroying buildings in Tel Aviv.
But it has not acted on its main options for retaliation, to attack US bases or choke off the 20 per cent of global oil shipments that pass through the Strait of Hormuz.
Attempting to strangle the strait could send global oil prices skyrocketing, derail the world economy and invite conflict with the US Navy's massive Fifth Fleet based in nearby Bahrain.
Oil prices jumped on Monday to their highest since January.Â
