The Treasury Department said the sanctions also were aimed at supporters of terrorism.
The sanctions targets are operating in Turkey, Spain, Germany, Georgia, Afghanistan, Iran, the United Arab Emirates, and Liechtenstein, the Treasury said.
"The global targets designated today play key roles in supporting Iran's nuclear program and active support for terrorism," David Cohen, the Treasury under secretary for terrorism and financial intelligence, said in a statement.
Cohen emphasized that the United States is implementing a temporary easing of some sanctions on Iran agreed in Geneva, but "the overwhelming majority of sanctions remain in effect and will continue to be vigorously enforced."
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Among the companies targeted was Spanish firm Advance Electrical and Industrial Technologies and DF Deutsche Forfait Aktiengesellschaft of Germany, for allegedly aiding Iran's nuclear and weapons proliferation activities.
The list includes some individuals accused of plotting attacks in Afghanistan.
Under the interim deal reached in November in Geneva, Iran agreed to freeze parts of its suspect nuclear program in return for some USD 7 billion in sanctions relief as it negotiates a final, comprehensive accord to dismantle its nuclear weapons capability.
The United States also agreed to refrain from slapping new sanctions on Iran.