The Obama administration on Thursday targeted more than two dozen companies and individuals for evading international sanctions against Iran or supporting its nuclear program, a signal that the U.S. will continue to enforce existing sanctions while pursuing a diplomatic resolution with Tehran.

The Treasury and State departments announced that the U.S. was freezing assets and banning transactions of entities and individuals they claim are involved in the proliferation of material used for making weapons of mass destruction or are attempting to evade sanctions.

“The conduct of these entities and individuals demonstrates Iran’s extensive efforts to conceal its evasive activities by using front companies in foreign countries to deceive foreign suppliers to support its illicit proliferation and evasion activities,” the departments said in a joint statement.

The U.S. and five other world powers recently signed a first-step agreement with Iran that is designed to prevent it from making progress toward the possible development of nuclear weapons — something Iran insists it is not trying to do.

Some U.S. lawmakers want to stiffen economic sanctions against Iran, but the administration is asking Congress to give diplomats a chance to reach a comprehensive agreement with Tehran.

Thursday’s announcement is a way for the administration to signal that it is serious about enforcing sanctions despite the agreement reached with Iran last month that provides it $6 billion to $7 billion in relief from U.S. economic penalties in exchange for a series of nuclear concessions.

The administration also committed to no new nuclear-related penalties for six months, a promise that upset members of both parties in Congress.

Secretary of State John Kerry and Treasury Secretary Jacob Lew met with much of the Senate in private on Wednesday in a renewed effort to put a hold on any legislation that might scuttle the nuclear deal.

(AP)