Iranian President Hassan Rouhani on Sunday cautioned US President Donald Trump about pursuing hostile policies against Tehran, saying "America should know ... war with Iran is the mother of all wars," the state new agency IRNA reported.
Iran faces increased US pressure and looming sanctions after Trump's decision to withdraw the United States from a 2015 international deal over Iran's nuclear programme.
Addressing a gathering of Iranian diplomats, Rouhani said: "Mr Trump, don't play with the lion's tail, this would only lead to regret," IRNA reported.
"America should know that peace with Iran is the mother of all peace, and war with Iran is the mother of all wars," Rouhani said.
"You are not in a position to incite the Iranian nation against Iran's security and interests," Rouhani said, in an apparent reference to reported efforts by Washington to destabilise Iran's Islamic government.
In Washington, US officials familiar with the matter told Reuters that the Trump administration has launched an offensive of speeches and online communications meant to foment unrest and help pressure Iran to end its nuclear programme and its support of militant groups.
Current and former US officials said the campaign paints Iranian leaders in a harsh light, at times using information that is exaggerated or contradicts other official pronouncements, including comments by previous administrations.