According to the Congressional Research Service, the deal appeared to violate the Iran Sanctions Act, meaning Daelim could have faced a range of punishments, including denial of federal contracts. That is because the law covers not only direct investments, such as the purchase of shares and deals that yield royalties, but also contracts similar to Daelim’s to manage oil and gas development projects.

But in 2009 the United States Army awarded the company a $111 million contract to build housing in a military base in South Korea. Just months later, Daelim, which disputes that its contracts violated the letter of the law, announced a new $600 million deal to help develop the South Pars gas field in Iran.

Now, though, frustration over Iran’s intransigence has spawned a growing, if still piecemeal, movement to more effectively use the power of the government purse to turn companies away from investing there.

Nineteen states — including New York, California and Florida — have rules that bar or discourage their pension funds from investing in companies that do certain types of business in Iran. Congress is considering legislation that would have the federal government follow suit, by mandating that companies that invest in Iran’s energy industry be denied federal contracts. The provision is modeled on an existing law dealing with war-torn Sudan.

Obama administration officials, while indicating that they were open to the idea, called it only one variable in a complex equation. Right now, the president’s priority is on breaking down Chinese resistance to the new United Nations sanctions, which apply across borders and are aimed squarely at entities that support Iran’s nuclear program.

But Representative Ron Klein, a Florida Democrat who wrote the contracting provision moving through Congress with the help of a lobbying group called United Against Nuclear Iran, said it offered a way forward with or without international agreement.

“We need to send a strong message to corporations that we’re not going to continue to allow them to economically enable the Iranian government to continue to do what they have been doing,” Mr. Klein said.