WASHINGTON—The U.S. moved to reimpose punishing sanctions on Iran and threatened even-tougher measures for later this year as the Trump administration sought to increase pressure on the Tehran regime to negotiate or step aside.

Trump administration officials publicly maintain that the campaign isn’t aimed at regime change, even as thousands of Iranians protest a deteriorating economy. But senior U.S. officials have repeatedly depicted Iranian leaders as corrupt ideologues and declared that Iranians should have the right to pick their own government.

President Trump signed on Monday the executive order restoring the sanctions, the broadest economic action the U.S. has taken against Tehran since the president in May said the U.S. would withdraw from the 2015 Iran nuclear accord, which had lifted them.

The sanctions will remain in effect, U.S. officials said, unless Tehran meets a dozen stringent demands, including that it cease its support for militant groups in the Middle East and end its enrichment of uranium.

Whether the administration’s calculation—that it can, in effect, drive a hard bargain with Iran or weaken the regime so it retrenches—pays off will depend on how vigorously the sanctions are enforced and whether Iran is able to circumvent them.