If they do not do so, future attacks will become much larger and much easier to carry out, says Trump in a live broadcast from the White House early on Sunday morning Swedish time.
American bomber planes struck a few hours earlier against three of the Iranian regime's most important nuclear facilities.
These are the enrichment facilities Fordo and Natanz, as well as the nuclear technology center Isfahan.
Our goal was to destroy Iran's enrichment capacity and a stop to the nuclear threat posed by the world's leading sponsor of terrorism, says Trump.
The attacks were a fantastic military success, Trump claims further.
The USA has not released documentation from the attacks, but Iranian authorities confirm that attacks have taken place at the three facilities.
An Iranian member of parliament claims that Fordo was not seriously damaged, according to state-run Iranian media. No one is also said to have been injured at any of the facilities as they had been evacuated before the attack, the member claims.
Iranian authorities state that they have not measured any increased radiation in the area.
Trump: "Historic"
The attack took place after several American bomber planes of the B-2 type left their base in the state of Missouri on Sunday and flew west over the Pacific Ocean.
"A full load of BOMBS was dropped on the primary facility, Fordo", Trump wrote during the night and called the attack a "historic moment" for the USA, Israel, and the world.
It is about six so-called "bunker-busting" bombs that weigh 15 tons each, reports Fox News.
Trump's decision to involve the USA directly in the war comes after Israel attacked Iran's air defense and arms factories. The war began with Israel's attack on its archenemy last Friday, since then the two countries have attacked each other on a daily basis.
Israel has also directed attacks against Iranian nuclear facilities, but only the USA is said to have heavy enough bombs to strike deep enough to damage Fordo, which is located deep in a mountain near the holy city of Qom, southwest of Tehran.
Has warned the USA
The USA's attack was coordinated together with Israel, according to Trump.
We worked as a team, like perhaps no team has ever worked before, said the president in his speech.
Iran's Foreign Minister Abbas Araghchi said earlier on Saturday that it "would be very unfortunate" if the USA were to become actively militarily involved in the war.
I think it would be very, very dangerous for everyone, he said then.
Iran has warned Washington that they will defend themselves and retaliate if the Americans were to actively enter the war. The USA has over 40,000 soldiers in the region who are stationed at several bases.
Either it will be peace or a tragedy will strike Iran that is much greater than what we have witnessed over the past eight days. Remember that there are many targets left, says Trump on Sunday morning.
