(WASHINGTON) -- President Donald Trump on Wednesday said a "massive Armada" was heading toward Iran and warned Tehran to make a nuclear deal or the next attack will be "far worse."
"A massive Armada is heading to Iran. It is moving quickly, with great power, enthusiasm, and purpose. It is a larger fleet, headed by the great Aircraft Carrier Abraham Lincoln, than that sent to Venezuela. Like with Venezuela, it is, ready, willing, and able to rapidly fulfill its mission, with speed and violence, if necessary," Trump wrote in a social media post.
"Hopefully Iran will quickly 'Come to the Table' and negotiate a fair and equitable deal - NO NUCLEAR WEAPONS - one that is good for all parties. Time is running out, it is truly of the essence! As I told Iran once before, MAKE A DEAL! They didn’t, and there was 'Operation Midnight Hammer,' a major destruction of Iran. The next attack will be far worse!" Trump added.
Last June, the U.S. struck three nuclear sites in Iran using bunker-busting bombs and cruise missiles. Trump, who had boasted the sites were "obliterated," has repeatedly warned Iran not to rebuild and rearm itself.
More recently, Trump's threatened to intervene in response to the killings of thousands of protesters in Iran.
Earlier this month, the administration sanctioned top Iranian officials they said were responsible for the nation's crackdown on peaceful demonstrators. Trump also announced a 25% tariff on any country doing business with Iran.
Last Thursday, Trump told reporters the U.S. was moving a large number of ships toward Iran "just in case."
"We'll see what happens. There was a big force going toward Iran. I'd rather not see anything happen, but we're watching that very closely," the president said.
U.S. Central Command on Monday confirmed the USS Abraham Lincoln and the three destroyers accompanying it had entered the Middle East area of operations earlier this week, bolstering the U.S. military presence in the region. The U.S. has maintained a steady aircraft carrier presence in the Middle East for decades.
The naval buildup adds some 5,000 American troops to the region, swelling an already robust American military footprint that includes multiple bases across the Middle East, such as Al Udeid Air Base in Qatar. In total, more than 30,000 U.S. troops are across the region. There hasn’t been a carrier in the region since last summer.
The Iranian Mission to the United Nations, in response to Trump's renewed threats on Wednesday, said in a statement that Iran would defend itself if necessary.
"Last time the U.S. blundered into wars in Afghanistan and Iraq, it squandered over $7 trillion and lost more than 7,000 American lives. Iran stands ready for dialogue based on mutual respect and interests -- BUT IF PUSHED, IT WILL DEFEND ITSELF AND RESPOND LIKE NEVER BEFORE!" the statement read.
Iran's foreign minister on Wednesday said he has not heard from the U.S. about a request for negotiations.
"Our position is clear. Negotiations cannot take place under threats, and any talks must be conducted in conditions where threats and excessive demands are set aside," said Iranian Foreign Minister Abbas Araghchi.
Secretary of State Marco Rubio, testifying before a Senate panel on Capitol Hill on Wednesday, characterized the U.S. force posture in the region, including the carrier, as a "baseline" needed to protect U.S. troops in the region as well as Israel, which remains under threat of Iranian drones and missiles.
"The baseline is this: we have 30 to 40,000 American troops stationed across eight or nine facilities in that region ... All are within the reach of an array of thousands of Iranian one-way [unmanned aerial vehicles] and Iranian short-range ballistic missiles that threaten our troop presence," he said.
"We have to have enough force and power in the region just on a baseline to defend against that possibility, that at some point, as a result of something, the Iranian regime decides to strike at our troop presence in the region," Rubio said.
Rubio also said Trump "reserves the preemptive defensive option" if the U.S. has indications Iran will strike U.S. forces.
"I think it's wise and prudent to have a force posture within the region that could respond and potentially -- not necessarily what's going to happen -- but if necessary, preemptively prevent the attack against thousands of American servicemen and other facilities in the region and our allies," the secretary said.
At least 6,126 people -- including 5,777 protesters -- have died in Iran's crackdown on nationwide protests, according to the latest data published by the Human Rights Activists News Agency, which relies on the work of activists inside and outside the country. ABC News cannot independently verify these numbers.
Rubio, when pressed for a State Department estimate, said "thousands" have died "for certain" in the Iranian crackdown.
"The protests may have ebbed, but they will spark up again in the future because this regime, unless they are willing to change and or leave, have no way of addressing the legitimate and consistent complaints of the people of Iran who deserve better," Rubio said.
Rubio asserted that protests across Iran due to a free-falling economy show "that regime is probably weaker than it has ever been."
He also said that it was an "open question" and "no one knows" who would fill a leadership void in Iran if Supreme Leader Ayatollah Ali Khamenei was removed from power.
If the regime were to fall, Rubio said the U.S. could "hope" for a "transition" like the one it is facilitating in Venezuela, but he "would imagine it would be far more complex … because you’re talking about a regime that’s been in place for a very long time."
ABC News' William Gretsky, Mariam Khan and Anne Flaherty contributed to this report.