Iranian Supreme Leader Ayatollah Ali Khamenei said Monday that the fate of the nuclear deal between Tehran and six world powers is "not clear," but added that one thing is certain: Iran will continue to oppose U.S. policies and influence.

"In their understanding of the deal, of which its fate is not clear since it is not clear if will be approved here or there, their intention was to find a way to penetrate into the country," he said in comments posted on his official website, referencing the United States, reported The Associated Press.

Lawmakers from both Iran and the U.S. are currently reviewing the deal, struck in Geneva on July 14 between Iran and the P5+1 world powers - the U.S., U.K., Russia, China, France and Germany. The deal would provide sanctions relief to Iran in exchange for it placing verifiable limits on its nuclear program. Congress has until Sept. 17 to vote to approve or reject the deal.

Khamenei has the final say in all state matters in Iran, and his comments suggest that he is allowing politicians to assume a role in reviewing the deal, according to AP. He has yet to publicly approve or disapprove of the accord, but he has spoken out against U.S. imperialism on a few occasions during and after the negotiations, promising to resist any American influence that may come as a result of the agreement.

"We blocked this path and will definitely block it in the future. We won't allow American political, economic or cultural influence in Iran," he said Monday, according to Newsmax.

On Saturday, Sen. Jeff Flake of Arizona, one of the only Republicans in Congress who was considering supporting the deal, said he could not back the agreement due to constraints that could prevent the U.S. from punishing Iran in the future for non-nuclear aggression in the Middle East, reported Politico.

If the deal is implemented in its entirety, the Iranian market will be open to new foreign investment after a period of prolonged isolation. While European firms may be allowed to establish a presence, Iran's fear of American influence and control will likely mean that U.S. businesses will be stonewalled for the time being.

"It will be a long time, regardless of whether the deal goes through, before U.S. businesses will fully operate in Iran," said Sarah Dayan, an analyst at The Risk Advisory Group in London, reported Newsmax.