"As a result of today's action, all property and interests in property of these individuals that are in the United States or in the possession or control of USA persons must be blocked and reported to [the Treasury's Office of Foreign Assets Control] OFAC", The statement continued.
"These measures represent a strong and proportionate response to Iran's increasingly provocative actions", Trump continued.
Last week the two countries came the closest in years to direct military confrontation after Iran shot down a USA drone. Iran says it will not be forced to the negotiating table.
"I'm not looking for war, and if there is, it will be obliteration like you've never seen before", Trump said on Sunday. In May, the Trump administration prohibited the purchase of Iranian iron, steel, aluminum and copper. Khamenei and his hardline allies are believed to have billions stockpiled and the new sanctions will directly target these cash assets, according to Treasury Department officials.
He added that the US and its allies started plotting against Iran since the very beginning of the victory of the Islamic Revolution, using different conspiracies and deceptions to stop, deviate or limit the scope of the Islamic Revolution. He also said the sanctions were in part in answer to the attack on the drone, but added that he would have ordered them even if that had not happened.
The eight commanders supervise the IRGC's "malicious regional activities", including ballistic missile programs, sabotage of commercial vessels in global waters, and its "destabilizing presence in Syria", the department said.
The U.S. military came close to attacking several Iranian military targets in answer to Iran's actions. The U.S. has blamed the attacks on Tehran, which has denied any wrongdoing.
"Why are we protecting the shipping lanes for other countries (many years) for zero compensation", he asked. He said they discussed "heightened tensions in the region and the need to promote maritime security" in the Strait of Hormuz, through which one-fifth of the world's traded oil passes.
Trump, Saudi crown prince discussed Iranian 'threat': White House
The tweet followed reports that Iran shot down one of U.S.'s surveillance drones over the Strait of Hormuz Thursday. Responding to the hawkish US official, Foreign Ministry spokesman Abbas Mousavi took to Twitter and asked, "Mr.
The newly announced sanctions show the United States is "doubling down" on its strategy, said Ariane Tabatabai, an expert on Iran at the RAND corporation. "We know what they've done", the official told reporters, adding that the deterrents would include cameras, binoculars and ships.
Saudi Arabia and the United Arab Emirates are alarmed by Iran's military reach and are working to limit its influence in the region.
The sultanate of Oman, meanwhile, said reports that it had served as a back channel for the United States to Iran in the aftermath of last week's drone shooting were "not true".
But Iran's United Nations ambassador said his country, already crippled by existing U.S. sanctions that include the blocking of most of its own crucial oil exports, is being subjected to "economic war".
Mr Trump said he decided the strike would have killed too many people.
His backing off on military strikes that were about to be launched in retaliation for the shootdown of an unmanned USA drone was just one of several recent tactical shifts by the White House on significant issues.
Khamenei, who was initially elected president of the nascent republic in 1981, has "possessions" worth an estimated at $200 billion, according to a Facebook post by the US embassy in Baghdad in April. However, just minutes before the attack was going to be carried out, he called it off. Pompeo met Monday with Saudi King Salman and Crown Prince Mohammed bin Salman.
"We look forward to a time in releasing sanctions, if they're willing to negotiate", the secretary said.
But some of his closest aides, such as national security advisor John Bolton and Secretary of State Mike Pompeo, are said to favour a far more muscular USA strategy.
While that decision not to order military strikes appears to have calmed tensions with Iran, at least somewhat, Trump's messages leave uncertainty about next steps.