The US Treasury has imposed sanctions against companies connected with the Iranian Revolutionary Guards.
The action extends earlier sanctions against the Guards and its construction company headquarters.
The BBC reports the intention is to freeze the foreign assets of four companies connected to Khatam al-Anbiya Construction and its chief officer.
The US Treasury said the company's profits help fund Iran's nuclear and missile programmes.
The company is the construction arm of the Iranian Revolutionary Guards.
Khatam al-Anbiya builds infrastructure like highways and tunnels, with the profits going into the Iranian military programme to develop what the US Treasury called "illicit activities".
According to a statement released on the US Treasury website, These included "WMD proliferation and support of terrorism".
President Barack Obama said on Tuesday the United States and its allies were moving "fairly quickly" toward adding new sanctions on Iran, in an attempt to curb its nuclear programme.
Tehran insists its nuclear programme is strictly peaceful in nature. But it has said it will continue to enrich uranium to 20%, higher than it has ever done before.
Experts say a nuclear weapon requires uranium to be enriched to 90%.
