Final answer:
The refusal by the United States to sell goods to Iran due to the perception of harboring radicals and terrorists is referred to as a trade embargo.
Step-by-step explanation:
The United States refusing to sell goods to Iran due to the perception that the country harbors radicals and terrorists is most accurately referred to as a trade embargo. A trade embargo is an economic boycott where a country ceases trade with another country unless certain conditions are met. In this case, the United States is imposing a trade embargo on Iran as a form of economic sanction.