Tehran issued President Donald Trump a fierce warning Sunday against launching an attack on Iran, threatening to carry out “painful attacks” in retaliation at a moment’s notice — and “without any limitations or considerations,” Al Jazeera reported.

Speculation swirled Saturday night that a U.S. attack in the Middle East may be “imminent” after Trump abruptly cut his weekend getaway in Maryland short — without explanation — and returned to the White House, his 35-year-old female aide Natalie Harp in tow.

Sunday morning, Trump told Fox News that he was in a “deciding mode” as to whether to authorize strikes in the Middle East, telling Fox News’ Trey Yingst that whatever he decided, “very big things” would take place in the “not-so-distant future.” He also told Yingst that “wiping Iran out” was actively being considered, insisting that “if and when” he decides to “blow the entire nation up,” Iranians had “better behave.”

Iranian officials, who are reportedly already preparing for the United States to resume hostilities, cautioned Trump to think carefully about his next move.

“Any mistake will result in painful attacks,” reads a statement published by Iran’s Khatam al-Anbiya military headquarters, according to Al Jazeera.

“According to information received, the United States — seeking to cover up its failures and achieve fabricated gains in a war that was launched based on Israeli lies and stage-managing and has been sustained through deception and trickery — has once again decided, with the green light from some regional countries, to resume actions against the Islamic Republic of Iran at a joint meeting in a European country.”

The Khatam al-Anbiya military headquarters also warned U.S. allies in the region that they would be “considered complicit” in any attack on Iran should Middle East U.S. bases be utilized.

“We warn that if the countries of the region — by continuing their dual policy toward the Islamic Republic of Iran — align with the Great Satan’s aggression against a powerful and sovereign Iran they will all be considered complicit in this evil and can no longer expect restraint or decency from Iran’s powerful armed forces,” the statement reads.