The renewal of the Iran Sanctions Act (ISA) became law Thursday without the signature of President Barack Obama.
The ISA extension was passed by overwhelming majorities in both houses of Congress. It was passed unanimously by the Senate.
The White House had previously expressed disapproval of the law. Obama's decision not to add his signature to it is seen as means of expressing disapproval and of attempting to alleviate Iranian concerns over the extension of sanctions.
Article 1, Section 7 of the US Constitution allows the President to ignore a law passed by Congress without signing the bill or expressing his objections to the law. The bill then automatically becomes law after 10 days.
The vote to extend the ISA was passed by veto-proof majorities.
White House press secretary Josh Earnest said: "The administration has, and continues to use, all of the necessary authorities to waive the relevant sanctions" which were lifted as part of the nuclear deal with Iran.
Iranian Supreme Leader Ayatollah Khamenei had threatened that Iran would "retaliate" and seek "revenge" if the ISA extension was passed.
This week, Iranian President Hassan Rouhani ordered Iranian scientists to begin work on nuclear powered marine vessels in response to the ISA.