TEHRAN — A new United States visa restriction that applies to Europeans and others who have visited so-called high-risk countries has led to angry reactions in Iran, where some leaders say the decision is a violation of the nuclear agreement reached in July.

Mohammad Javad Zarif, Iran’s foreign minister, told state media on Monday that the visa restriction was an “obstacle, placed by some individuals,” that he hoped would soon be resolved. Mr. Zarif referred to a letter sent by Secretary of State John Kerry on Saturday, asserting that the restriction would not affect the nuclear agreement.

The letter, obtained and leaked by the National Iranian American Council, an advocacy group based in Washington, hinted that President Obama would use his executive authority to exempt Iran from the visa restriction, which was passed almost unanimously in Congress. Mr. Obama signed it into law on Friday.

The restriction, a security step arising from the recent terrorist attacks in Paris and San Bernardino, Calif., prohibits visa-free travel to the United States for anyone who has visited or holds citizenship in Syria, Iraq, Sudan and Iran.