The Trump administration has slapped 18 Iranian individuals and groups with sanctions for aiding the country's non-nuclear weapons programmes.
The move aims to show that President Donald Trump is staying tough on Iran despite his moves to let the nuclear agreement remain in place for now.
The latest attempt to clamp down on Iran's military financing ranged from an Iranian-based company that aided the country's drone programme to a Turkey-based provider of naval equipment and a Chinese network that helped secure electronics for Tehran.
The sanctions freeze any assets in the US and prevent Americans from doing business with them.
Treasury secretary Steven Mnuchin said the sanctions "send a strong signal that the United States cannot and will not tolerate Iran's provocative and destabilising behaviour".
"This administration will continue to aggressively target Iran's malign activity, including their ongoing state support of terrorism, ballistic missile programme, and human rights abuses."
The announcement came hours after the Trump administration told Congress for a second time that Iran is complying with the nuclear deal and can retain sanctions relief, but officials insisted Tehran was breaching "the spirit" of the deal.
Mr Trump, who lambasted the 2015 pact as a presidential candidate, gave himself more time to decide whether to scuttle it or let it stand.
Instead, senior Trump administration officials sought to emphasise their deep concerns about Iran's non-nuclear behaviour and vowed that those transgressions will not go unpunished.
During the campaign, Mr Trump told the American Israel Political Action Committee: "My number one priority is to dismantle the disastrous deal with Iran."
In a shift from that earlier threat to dismantle the deal, officials said the administration was working with US allies to try to fix the deal's flaws, including the expiration of some nuclear restrictions after a decade or more.
The officials also said the US would slap Tehran with new sanctions penalising it for developing ballistic missiles and other activity.
Mr Trump, secretary of state Rex Tillerson and "the entire administration judge that Iran is unquestionably in default of the spirit" of the agreement, one official said. That assessment carries no legal force, while Mr Trump's certification that Iran is technically complying clears the way for sanctions to remain lifted.
