In a statement carried by the state-run IRNA news agency, the Foreign Ministry said Iran "will not accept any change in the deal, neither now nor in future," adding that it will "not take any action beyond its commitments."
It also said Iran would not allow the deal to be linked to other issues, after Trump suggested that the sanctions relief under the deal be tied to Iran limiting its long-range ballistic missile program.
Trump on Friday extended the waivers of key economic sanctions that were lifted under the agreement limiting Iran's nuclear program. But he said he would work with European allies to remove so-called "sunset clauses" that allow Iran to gradually resume advanced nuclear activities in the next decade.
He paired Friday's concession with other, targeted sanctions on Iran for human rights abuses and ballistic missile development. The Treasury Department's action hits 14 Iranian officials and companies and businessmen from Iran, China and Malaysia, freezing any assets they have in the U.S. and banning Americans from doing business with them.
The Iranian statement said the targeting of one of the officials, judiciary chief Sadegh Amoli Larijani, "crossed all behavioral red lines of the international community." It said the sanctions are against international law and go against U.S. commitments, saying they would bring a "strong reaction" from Iran.
The 2015 nuclear accord, reached after months of painstaking negotiations with the U.S., Britain, France, Germany, China and Russia, lifted international sanctions in exchange for Iran limiting its nuclear program. Trump has repeatedly criticized the accord, while Iran has accused the U.S. of failing to comply with it. The next sanctions waivers are due in May.