Gov. Mike Pence and 14 other Republican governors sent a letter Tuesday to President Barack Obama expressing their opposition to the Iran nuclear power agreement.
The governors also said they will continue to enforce state-imposed sanctions against Iran.
"The lifting of federal sanctions that will result from this agreement will only result in Iran having more money available to fund terrorist groups and attacks," the governors said in their letter.
"The people of our states will not be safer as a result of this agreement, much less citizens of countries like Israel which Iran has threatened to destroy," they said.
They concluded that they "intend to ensure that the various state-level sanctions that are now in effect remain in effect. These state-level sanctions are critically important and must be maintained."
Indiana laws prohibit the investment of state pension funds in Iranian-controlled interests, and forbid state and local government contractors from investing more than $20 million in goods, services or credit in the Iranian energy sector.
Other governors signing the letter included Govs. John Kasich of Ohio, Scott Walker of Wisconsin, Chris Christie of New Jersey and Bobby Jindal of Louisiana, each of whom seeks the Republican presidential nomination in 2016.
The governors of Arizona, Arkansas, Florida, Mississippi, North Dakota, Oklahoma, South Carolina, South Dakota, Texas and Utah also signed the letter.
Congress is scheduled to begin debating today legislation that would block the Iran nuclear deal, which was signed in July by Iran, the U.S., the United Kingdom, France, Germany, Russia and China.
The White House appears to have enough supporters of the deal among Democratic senators to sustain a presidential veto of any Republican-passed legislation to thwart the agreement, which aims to prevent Iran from developing nuclear weapons during the next 15 years.