"The world should know," Pompeo said, "that we will continue to make sure it's understood that this effort that we've engaged in to deny Iran the resources to foment terror, to build out their nuclear weapon system, to build out their missile program, we are going to deny them the resources they need to do that thereby keeping American interests and American people safe all around the world."

Secretary of State Mike Pompeo described the new sanctions as "significant" as he left Washington on Sunday for a trip to Saudi Arabia and the United Arab Emirates to continue the Trump administration's effort to build a coalition of allies to counter Iran. Pompeo met Monday with Saudi King Salman and Crown Prince Mohammed bin Salman.

President Trump said that late Thursday he had canceled a retaliatory strike against several Iranian targets. But on Thursday, according to U.S. news accounts, Trump also approved U.S. Cyber Command attacks on an Iranian intelligence group's computer systems used to control missile and rocket launches.

The move comes amid rising concerns about a potential armed confrontation between the two nations after U.S. officials recently blamed Tehran for mine attacks on two oil tankers in the Strait of Hormuz, allegations Tehran denies, and Iran's shoot-down of a U.S. drone last week.

U.S. President Donald Trump has signed an executive order imposing fresh sanctions on Iran, seeking to put additional pressure on the country's economy in order to extract changes in behavior from its government.

Concern about a potential armed confrontation between Iran and the U.S. has been growing since U.S. officials recently blamed Tehran for mine attacks on two oil tankers in the Strait of Hormuz, allegations Tehran denies, and Iran's shoot-down of a U.S. drone last week.

President Trump said that late Thursday he had canceled a retaliatory strike against several Iranian targets. But on Thursday, according to U.S. news accounts, Trump also approved U.S. Cyber Command attacks on an Iranian intelligence group's computer systems used to control missile and rocket launches.

Iran has denied working on nuclear weapons and signed an agreement in 2015 with the United States, Britain, China, France, Russia and Germany to allay those concerns by limiting its nuclear activity in exchange for sanctions relief.

But U.S.-Iran relations have deteriorated during Trump's tenure, particularly since his decision last year to withdraw from the nuclear deal and reimpose economic sanctions. Trump objected to the deal as being too weak and not including limits on Iran's ballistic missile program, although the United Nations' atomic watchdog agency says Tehran is complying with the international accord.

Iran has defended its missile work as legal and necessary for its defense. Tehran has sought support from the remaining signatories to the 2015 agreement to provide the economic relief it wants, especially with its key oil exports as the U.S. has tightened sanctions in an attempt to cut off Iranian oil shipments.

Pompeo said the new sanctions Monday "will be a further effort to ensure that their capacity not only to grow their economy but to evade sanctions becomes more and more difficult, and it will be an important addition to our capacity to enforce sanctions against Iran to ultimately achieve the objective that we've laid out."

Trump said in a series of tweets Saturday about the sanctions that he looks forward to the day when "sanctions come off Iran, and they become a productive and prosperous national again -- The sooner the better!" He also said in an interview with NBC's Meet the Press that he is "not looking for war" with Iran and is willing to negotiate with its leaders without preconditions.

