Iranian President Masoud Pezeshkian on Tuesday warned that his country would respond harshly to any act of aggression, following a renewed threat of military action from US President Donald Trump.

He made the statement on social media platform X following comments by Trump on Monday, who threatened Iran with a major military strike if it resumed its ballistic missile or nuclear weapons programs.

"The Islamic Republic of Iran's response to any cruel aggression would be harsh and regret-inducing," Pezeshkian said.

Trump, speaking to reporters in Florida while welcoming Israeli Prime Minister Benjamin Netanyahu, said on Monday, "Now I hear that Iran is trying to build up again, and if they are, we're going to have to knock them down."

In response, Ali Shamkhani, a political advisor to Iran's Supreme Leader Ali Khamenei and representative in the country's Defense Council, posted on X that Iran's missile and defense capabilities "are not containable or permission-based."

"Any aggression will face an immediate harsh response beyond its planners' imagination," he added.

Tensions between Iran and the United States have escalated after a series of strikes in June. On June 13, Israel launched airstrikes on several locations in Iran, including nuclear and military sites, killing senior commanders, nuclear scientists and civilians. On June 22, U.S. forces bombed the Iranian nuclear facilities at Natanz, Fordow and Isfahan.