Donald Trump has warned Iran of consequences "the likes of which few throughout history have ever suffered" if it threatens the US.
In a direct message to Iranian President Hassan Rouhani, the US president - writing in capital letters - said: "NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE.
"WE ARE NO LONGER A COUNTRY THAT WILL STAND FOR YOUR DEMENTED WORDS OF VIOLENCE & DEATH. BE CAUTIOUS!"
On Sunday, Iran's semi-official ISNA news agency reported Mr Rouhani as urging Mr Trump to "make peace" with Iran.
The report quoted Mr Rouhani as saying that "American must understand well that peace with Iran is the mother of all peace and war with Iran is the mother of all wars".
The Iranian leader warned Mr Trump to stop "playing with the lion's tail" and threatening Iran, "or else you will regret it".