The U.S.'s drone violation of Iran's airspace started new tensions in the region, Iranian President Hassan Rouhani said Sunday.
On Thursday, an Iranian missile destroyed a U.S. Global Hawk surveillance drone, an incident that Washington said happened in international airspace. Trump later said he had called off a military strike to retaliate because it could have killed 150 people.
Tehran repeated on Saturday that the drone was shot down over its territory and said it would respond firmly to any U.S. threat.
Speaking in Washington on Saturday before heading to the U.S. presidential retreat at Camp David, Trump indicated the government was taking a diplomatic path to put pressure on Tehran by moving to impose new sanctions.
Military action was "always on the table," the president said, but he added that he was open to quickly reaching a deal with Iran that he said would bolster the country's flagging economy.
"We will call it 'Let's make Iran great again,'" Trump said.
He later wrote on Twitter from Camp David: "We are putting major additional Sanctions on Iran on Monday. I look forward to the day that Sanctions come off Iran, and they become a productive and prosperous nation again."
The Trump administration has sought to use promises of economic revival to solve other thorny foreign policy challenges, including the Israel-Palestinian peace process, with the White House outlining on Saturday a plan to create a global investment fund to lift the Palestinian and neighboring Arab state economies.
Both Trump and Tehran have said they are not seeking a war, but Iran has warned of a "crushing" response if attacked.
"Regardless of any decision they (U.S. officials) make... we will not allow any of Iran's borders to be violated. Iran will firmly confront any aggression or threat by America," Foreign Ministry spokesman Abbas Mousavi told the semi-official Tasnim news agency on Saturday.
A senior commander of the elite Revolutionary Guards struck a similarly defiant note, in comments quoted by the Islamic Republic News Agency (IRNA).
"If the violation is repeated then our response will be repeated," said Brigadier General Amirali Hajizadeh, head of the Guards' aerospace division. "It's possible that this infringement of the Americans was carried out by a general or some operators."
Iran's Foreign Ministry summoned a United Arab Emirates envoy on Saturday because the UAE allowed the drone to be launched from a U.S. military base on its territory, the Fars news agency reported.
The Iranian foreign minister, Mohammad Javad Zarif, published a map on Twitter with detailed coordinates which he said showed the drone was flying over the Islamic Republic's territorial waters.
U.S. Secretary of State Mike Pompeo said in a statement on Saturday that the United States had "shown beyond any doubt" that the drone was in international airspace.
"When the Iranian regime decides to forgo violence and meet our diplomacy with diplomacy, it knows how to reach us," he said. "Until then, our diplomatic isolation and economic pressure campaign against the regime will intensify."
He also denied reports U.S. forces would evacuate personnel from a military base in neighboring Iraq over what military sources had said were "potential security threats."
