The governing body of the watchdog, the International Atomic Energy Agency, meeting in Vienna, Austira, also expressed “serious concern” about potential military aspects of Iran’s nuclear program. 

Administration officials held up the statement as a victory for President Obama’s diplomatic efforts to coax both Russia and China to increase the pressure on Iran. They said that they had begun working on a sanctions package, which would be brought before the United Nations Security Council if Iran did not meet the year-end deadline imposed by President Obama to make progress on the issue.

“Today’s overwhelming vote at the I.A.E.A.’s Board of Governors demonstrates the resolve and unity of the international community with regard to Iran’s nuclear program,” the White House spokesman, Robert Gibbs, said in a statement. “Indeed, the fact that 25 countries from all parts of the world cast their votes in favor shows the urgent need for Iran to address the growing international deficit of confidence in its intentions.”

In recent weeks, the Obama administration has been painstakingly wooing Russia and China, the two permanent members of the Security Council most averse to imposing sanctions.