Iran would be prepared to respond to a possible confrontation with the U.S. after the Trump administration dispatched troops to the region and arranged the sale of billions of dollars in weapons to its Arab allies, top Iranian officials said.

President Trump on Friday said he was sending 1,500 more troops to the Middle East amid rising tensions with Iran. On the same day, his administration invoked a rarely used provision of American arms control laws to declare an emergency to rush through weapons sales to Saudi Arabia and...