Hassan Rouhani spoke after France's Emmanuel Macron flew to Washington to meet with the president, and try to convince him to stick with the landmark pact.
Iranian President Hassan Rouhani on Wednesday dismissed Donald Trump as unqualified to deal with important international issues amid U.S. threats to potentially walk away from the landmark nuclear deal with Tehran.
Rouhani spoke on state TV after French leader Emmanuel Macron flew to Washington to meet with the U.S. president. Among Macron's aims was convincing Trump to stick with the 2015 pact, which saw Iran sharply curtail its nuclear program in exchange for the lifting of sanctions.
Rouhani, a reforming cleric, unleashed a series of insults during his speech.
"You don't have any background in politics," Reuters quoted him saying in comments directed at Trump. "You don't have any background in law. You don't have any background on international treaties."
Rouhani added: "How can a tradesman, a merchant, a building constructor, a tower constructor make judgments about international affairs?"
Leaders in both countries have engaged in an escalating war of words over the Obama-era nuclear accord, which Trump has derided as a "terrible deal."
On Tuesday, Trump said was "insane" and "ridiculous" that the agreement between Iran and the U.S., China, Russia, France, U.K., Germany and the European Union did not cover Tehran's possession of ballistic missiles or its destabilizing actions in places like Yemen or Syria.
Trump also warned that if Iran restarts its nuclear program it would "have bigger problems" than ever before.
The White House has hoped to enlist European allies in new negotiations with Iran, but Europeans — including Macron — have warned that doing so would alienate Iran.
In May, Trump will once again have to decide whether to recertify the Iran deal to Congress.
If he doesn't, he could begin the process to reversing the deal.
Iran has threatened to resume enrichment activities if the agreement collapses.