(Reuters) - U.S. Secretary of State Mike Pompeo launched a rhetorical assault on Iran’s leaders on Sunday, comparing them to a “mafia” and promising unspecified backing for Iranians unhappy with their government.

U.S. Secretary of State Mike Pompeo holds a press briefing at U.N. headquarters in New York City, New York, U.S., July 20, 2018. REUTERS/Brendan McDermid

Pompeo, in a California speech to a largely Iranian-American audience, dismissed Iranian President Hassan Rouhani and Foreign Minister Javad Zarif, who negotiated a nuclear deal with the United States and five other countries, as “merely polished front men for the ayatollahs’ international con artistry.”

U.S. President Donald Trump withdrew in May from the 2015 nuclear accord designed to stop Iran from developing nuclear weapons. Tehran has said its nuclear work is just for electricity generation and other peaceful projects.

Iran “is run by something that resembles the mafia more than a government,” Pompeo said, citing what he called Iranian leaders’ vast wealth and corruption.

Pompeo’s speech was the latest step in a communications offensive launched by the Trump administration that is meant to foment unrest in Iran and help pressure its government to end its nuclear program and support of militant groups, U.S. officials familiar with the matter said.

The offensive is meant to work in concert with severe economic sanctions that Washington plans to reimpose in the coming months, including on Tehran’s oil exports, its principal revenue generator.

The United States will work with countries that import Iranian oil “to get imports as close to zero as possible” by Nov. 4, Pompeo said.

Rouhani cautioned Trump on Sunday about pursuing hostile policies against Tehran, saying: “War with Iran is the mother of all wars.” But he did not rule out peace between the two countries, which have been at odds since the 1979 Islamic Revolution.

“You are not in a position to incite the Iranian nation against Iran’s security and interests,” Rouhani said, in an apparent reference to reports of efforts by Washington to destabilize Iran’s Islamic government.

Trump responded to Rouhani in a tweet late on Sunday, saying: “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!”

‘LONG-IGNORED VOICE OF PEOPLE’

Publicly, the Trump administration says its policy with Iran is not “regime change,” but to change Tehran’s behavior so it stops nuclear and missile work, support for proxies in the Middle East and backing of militant groups.

“While it is ultimately up to the Iranian people to determine the direction of their country, the United States ... will support the long-ignored voice of the Iranian people,” Pompeo said.

Pompeo spoke at the Ronald Reagan Presidential Library in Simi Valley, California, to a packed house of about 1,000 people. He received frequent applause, although one audience member heckled him over the Trump administration’s immigration policies.

Several dozen protesters lined the route to the site, including one group that distributed fliers opposing both Iran’s current government and any U.S. intervention in Iran.

Pompeo said senior Iranian leaders had benefited from embezzlement, sweetheart deals and other ill-gotten gains.

Iran’s ayatollahs, he said, were “hypocritical holy men” who “seem more concerned with riches than religion.”

Pompeo said the U.S. government broadcasting agency was launching a 24/7 Farsi-language channel on TV, radio, digital and social media platforms. The U.S. government also is taking steps to help Iranians get around internet censorship, he said.