No Oil Producing and Exporting Cartels Act of 2007 or NOPEC - Amends the Sherman Act to declare it to be illegal and a violation of the Act for any foreign state or instrumentality thereof to act collectively or in combination with any other foreign state or any other person, whether by cartel or any other association or form of cooperation or joint action, to limit the production or distribution of oil, natural gas, or any other petroleum product (petroleum), to set or maintain the price of petroleum, or to otherwise take any action in restraint of trade for petroleum, when such action has a direct, substantial, and reasonably foreseeable effect on the market, supply, price, or distribution of petroleum in the United States. Denies a foreign state engaged in such conduct sovereign immunity from the jurisdiction or judgements of U.S. courts in any action brought to enforce this Act. States that no U.S. court shall decline, based on the act of state doctrine, to make a determination on the merits in an action brought under this Act. Authorizes the Attorney General to bring an action in U.S. district court to enforce this Act. Makes an exception to the jurisdictional immunity of a foreign state in an action brought under this Act.