Iran's Khamenei says Trump shows real face of America
In his first speech since Mr Trump took office, Mr Khamenei said the president had exposed "political, economic, moral and social corruption" in the US.
The response follows Mr Trump's imposition of new sanctions on Iran over a ballistic missile test.
Mr Trump has also been a fierce critic of the landmark nuclear deal struck between Iran and world powers in 2015.
Mr Khamenei, addressing military commanders in the capital Tehran, said Mr Trump was trying to frighten Iranians, but would fail.
"We are thankful for this person who has arrived [President Trump]. Our thanks is for making our life easy as he showed the real face of America," he said.
"What we have been saying for more than 30 years about the political, economic, moral and social corruption in the US ruling system, this person arose during the election campaign and... has confirmed it.