Trump told host Maria Bartiromo he wrote a letter to Iranian Supreme Leader Ayatollah Ali Khamenei.

“I’ve written them a letter, saying I hope you’re going to negotiate because if we have to go in militarily it’s going to be a terrible thing for them,” Trump said during the interview with Bartiromo, parts of which aired Friday.

“You can’t let them have a nuclear weapon.”

Iran said it has not received a letter from Trump, the Permanent Mission of the Islamic Republic of Iran to the United Nations told CBS News in a statement.

In late February, the Trump administration sanctioned a combination of 30 individuals and vessels involved in illicit sales of Iranian oil.

Earlier that month, Trump signed a memorandum to restore a so-called maximum pressure campaign on Iran. The tactic was first used during his first administration with the goal of reaching a new nuclear deal with Tehran. No agreement materialized as Iran escalated its nuclear program.

In 2018, Trump pulled out of the 2015 nuclear deal with Iran signed under former President Barack Obama, calling the pact “defective to its core.”

Since 2018, Iran has been increasing its stockpile of enriched uranium with the goal of producing nuclear weapons.

“I said, ‘I hope you’re going to negotiate,’ because it will be a lot better for Iran. I think they want to get that letter. The other alternative is we have to do something because you can’t let them have a nuclear weapon,” Trump said during an interview clip Friday.

Last July, the United States sanctioned three United Arab Emirates companies and 11 vessels used to transport Iranian petroleum and petrochemical products. The retaliatory move was made after Tehran expanded its nuclear program.

At the time, then-Secretary of State Antony Blinken said Iran was expanding its “nuclear program in ways that have no credible peaceful purpose.”