UNITED NATIONS (CNN) --Mahmoud Ahmadinejad insisted in a speech at the U.N. that Iran's nuclear activities are peaceful.
The resolution also offers Tehran incentives to do so.
The measure was designed to send the message "that our resolve has not weakened on this issue," British Foreign Secretary David Miliband said.
He said the sanctions remain in place "in the face of Iranian defiance" of U.N. inspectors.
The resolution comes after Iran failed to respond positively to an international offer of economic incentives in exchange for suspending its nuclear activity.
The approval of the resolution signaled a compromise among the "P5 plus one": the five permanent members of the U.N. Security Council, Britain, China, France, Russia and the U.S., plus Germany.
Though Russia and China opposed expanding sanctions against Iran, the rest of the countries were ready to move forward.
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Russia had threatened to boycott the meeting over recent tensions with the United States regarding the Georgian conflict.
The countries agreed to limit the resolution to reaffirming the previous sets of sanctions, which include economic measures and arms embargoes, while noting that Iran has not complied in the wake of past sanctions, a U.N. official said.
Tehran has called the sanctions "futile and ineffective."
In a blistering speech Tuesday before the United Nations General Assembly -- from which U.S. diplomats were absent -- Iranian President Mahmoud Ahmadinejad insisted that Iran's nuclear activities are peaceful and criticized the same powers for seeking to hinder it "by exerting political and economic pressures against Iran and also threatening and pressuring" the International Atomic Energy Agency.
Those powers are building nuclear arsenals themselves, unchecked by anyone, he said. "The tragedies of Hiroshima and Nagasaki were perpetrated by one of them."
He painted the United Nations and its Security Council as ineffectual, in part because of the influence of such powers.