Iran agreed to curb its nuclear enrichment program under the terms of a deal reached in Geneva, Switzerland, in November with Western negotiators. In return, Tehran gets some relief from economic sanctions.
Zarif said Wednesday he was frustrated with testimony from U.S. Undersecretary for Political Affairs Wendy Sherman.
Sherman said in written testimony to the Senate Committee on Foreign Relations the U.S. government views Iran's nuclear ambitions as "one of the most serious threats to U.S. national security." The interim nuclear deal was "an important first step." A long-term deal, she said, isn't based on trust but "verifiable actions and constraints that convince us and the international community that Iran is not building a nuclear bomb."
Zarif was quoted by the semiofficial Fars News Agency as saying Sherman needed to "review the realities" of the situation.
"Iran's nuclear technology is not negotiable," he added.
Iran says its nuclear program is meant for peaceful purposes.
Iranian officials this week said Tehran is frustrated with rhetoric coming from U.S. officials as negotiators prepare for a round of talks Feb. 18 in Vienna.