U.S. Secretary of State Mike Pompeo on Monday warned all banks and businesses against dealing with Iran's Revolutionary Guards after Washington designated the elite unit as a terrorist group.

“The leaders of Iran are racketeers, not revolutionaries,” Pompeo said in a press conference after U.S. President Donald Trump made the blacklisting announcement.

“Businesses and banks around the world now have a clear duty to ensure that companies with which they conduct financial transactions are not conducted with the IRGC in any material way.”

Pompeo noted that the designation will take effect in one week.

Pompeo said the designation recognizes a "basic reality", deeming it as a direct response to an outlaw regime and should surprise no one".

“The IRGC masquerades as a legitimate military organization, but none of us should be fooled.”

Pompeo said that the IRGC support Hezbollah "militia" in Lebanon, reiterating that the U.S. will not tolerate the continued rise of Hezbollah inside the country.

When asked about whether Lebanese Parliament Speaker Nabih Berri might be sanctioned over his close ties with Hezbollah, Pompeo did not deny the reports, saying that the U.S. would mull sanctions against anyone who supports Hezbollah.

"On my most recent trip to Beirut, I made clear to the Lebanese leadership, including in conversations with Speaker Nabih Berri, that America was not going to tolerate the continuous rise of Hezbollah inside of the country, that it wasn’t in the best interest of the Lebanese people to have an armed terror group, underwritten by the very Iran that we are speaking about today, to continue to have significant sway inside of that nation by use of force," he said.

"This is not about political parties but this is about armed forces inside the country of Lebanon. We made very clear that we will continue to evaluate sanctions for all those who are connected to Hezbollah."