Iran and Western negotiating partners agreed from Geneva, Switzerland, to implement the terms of a November interim nuclear deal starting Jan. 20. Iran under the terms of the deal suspends some of its nuclear research activity in exchange for relief from certain economic sanctions.
U.S. Rep. Ed Royce, R-Calif., chairman of the committee, said he was concerned about Iran's sincerity given recent statements it would continue its work on uranium enrichment.
"I'm concerned that this agreement takes us down that path where sanctions pressure is relieved, but Iran maintains its ability to produce a nuclear weapon," he said in a statement Sunday.
Iran had expressed frustration it was still the target of sanctions pressure. The U.S. government countered it was enforcing existing sanctions and viewed new sanctions as counterproductive.
Royce in July introduced legislation that would tighten the sanctions pressure on Iran.
U.S. President Barack Obama said in a statement Sunday the road ahead would be tough "but for the sake of our national security and the peace and security of the world, now is the time to give diplomacy a chance to succeed."