BEIJING — Treasury Secretary Timothy F. Geithner pressed Chinese senior leaders on Wednesday to join an American-led campaign to reduce sharply Iran’s lucrative oil exports because of its nuclear program. And as they had before Mr. Geithner’s arrival here on Tuesday, Chinese officials said publicly that they wanted no part of the effort.

But President Obama’s administration, armed with a new law that would punish foreign financial institutions that deal with Iran, appeared undeterred.

“We are in the early stages of a broad global diplomatic effort to take advantage of this new legislation to significantly intensify the pressure on Iran,” a senior administration official said on Wednesday. “We are telling them what’s important to us, and they are listening.” The official spoke on the condition of anonymity because of the diplomatic importance of the issues.

The discussions on Iran were a highlight of Mr. Geithner’s separate meetings with Prime Minister Wen Jiabao of China, Vice President Xi Jinping and Vice Prime Minister Li Keqiang, which covered the landscape of economic and trade relations between China and the United States. Because the Treasury Department is responsible for enforcing sanction laws, Mr. Geithner spent time explaining the new legislation, which would generally deny access to the American financial system for foreign financial institutions that do business with Iran’s Central Bank.