White House has urged Iran to take Donald Trump’s warning seriously according to Press Secretary Caroline Levitt in a statement issued Monday local time. She emphasized the Trump administration’s firm stance against terrorist attacks.

Warning follows U.S. airstrikes targeting Houthi rebel positions in Yemen including key locations in the capital, Sanaa. Attacks carried out over the past two days resulted in significant casualties.

Iran’s Foreign Ministry spokesperson, Ismail Baghaei, condemned U.S. strikes calling them violations of UN Charter and international law. Baghaei vowed firm and specific response to what he described as aggression against Iran’s security and territorial integrity.

Read more: Gaza Crisis Deepens as Sudden Israeli Airstrikes Kill Hundreds Amid Rising Tensions

Addressing Trump’s recent letter, Baghaei criticized U.S. for sending conflicting messages, claiming that Trump’s words often contradict his actions. He also blamed Israel for escalating tensions in region accusing it of endangering Iran’s peaceful nuclear facilities.

Baghaei further argued that Israel remains primary beneficiary of rising regional instability.