The spokesman for the Khatam al-Anbiya Central Headquarters issued a formal warning on March 29 against any US ground operation or seizure of Persian Gulf islands, threatening that American troops would face "humiliating captivity, dismemberment and disappearance," Mehr News Agency reported.

"The warriors of Islam have long been awaiting such actions to prove that aggression and occupation will result in nothing but humiliating captivity, dismemberment and disappearance of the aggressors, and that American commanders and soldiers will become good prey for the sharks of the Persian Gulf," Brigadier General Ebrahim Zolfaghari said in a statement. 

The spokesman dismissed Trump's credibility in blunt terms, describing him as "the most dishonest president among world nations" and accusing him of erratic decision-making.

"Trump beats the drum of threat over an issue one morning, only to retreat by evening. One moment he speaks of negotiation, and hours later he decides to wage war," the spokesman said.

Parliament Speaker Mohammad Bagher Ghalibaf echoed the warning in a message marking the 30th day of what he called the Ramadan War, saying Iran's fighters were ready and waiting.

"The enemy openly sends messages of negotiation and dialogue while secretly planning a ground attack. Unaware that our men are waiting for US soldiers to enter on the ground, to set them on fire and punish their regional partners forever," Ghalibaf said.

Ghalibaf attacked Trump directly, saying the US president had been unable to rally European support, had lost control of energy markets and was now seeking through diplomacy what he had failed to achieve on the battlefield.

"The enemy that claimed it had destroyed our air force, navy and missile forces, and had planned the collapse of the Islamic Republic, has now set its operational ambition to opening the Strait of Hormuz, a strait that was open before the Ramadan War began," Ghalibaf said.

He called on Iranians not to abandon public demonstrations, saying the street was as much a battlefield as the front lines.

"Missiles, the street and the strait are squeezing the enemy's throat. Just as your soldiers will not abandon the missiles and the Strait of Hormuz, do not abandon the strait of the street," Ghalibaf said.

Both statements came as Iran marked 30 days since the US and Israeli strikes began on February 28, with Ghalibaf saying the war had reached its most critical phase.