"The Treasury Department will continue to sever Hezbollah from the global financial system, and we will be relentless in identifying, exposing, and dismantling Hezbollah's financial support networks globally", Treasury Secretary Steven Mnuchin said in the statement.
The United States has sanctioned Hezbollah in the past, with the House of Representatives approving in October new sanctions on the Lebanon-based terrorist group.
General Heidari said Iran supports regional states which have stood up against the terrorist groups and crises created by the U.S. and its allies in the region.
While the USA government has used sanctions for years as part of an attempt to constrain Hezbollah's activity, officials acknowledge the challenge they face because of Iran's continued support for the group. The Trump administration said companies and their executives act on Tabaja's behalf, forming "conduits" of funding for the Lebanon-based terror group.
They must also grapple, senior officials said in describing the new sanctions, with the fact that Iran and Hezbollah may prioritize financial backing for militant activities even when overall resources decline.
The U.S. accuses Tabaja of being a top financier for Hezbollah.
The U.S. estimates Iran sends Hezbollah about $700 million a year and officials say that Hezbollah has become Iran's main proxy in the Arabic-speaking world.
Yet in targeting Hezbollah so forcefully, the Trump administration has raised hard questions about how the US can justify continued close ties to Lebanon. He said past investigations had also exposed complicity or involvement by parts of Lebanon's government in Hezbollah's money-laundering operations.
The six individuals were targeted because they are linked to financier Adham Tabaja and his company, Al-Inmaa Engineering and Contracting.
More such targeted sanctions are expected in the months ahead, they said.
The sanctions aim to squeeze Tabaja, who the United States has already labeled a global terrorist and is thought to be one of Hezbollah's top five funders.
"We will no longer allow corrupt Hezbollah and other Iranian regime cronies to hide their crimes behind front companies", White House spokeswoman Sarah Huckabee Sanders said on Twitter.
The anonymous administration official denied this would be the case, telling The Daily Star the US government was mindful of the Lebanese economy.