US president Barack Obama has said he and Chinese president Hu Jintao want to ensure that Iran lives by "international rules and norms" amid fresh allegations that Tehran is conducting nuclear weapons work in secret.
Mr Obama's meeting with his Chinese counterpart on Saturday followed a lengthy discussion with Russian president Dmitry Medvedev on the sidelines of the Asia-Pacific summit in Hawaii.
As he met with Mr Medvedev, the US leader told reporters the US and Russia intend to "shape a common response" to Iran's nuclear efforts.
The meetings came the day after the International Atomic Energy Agency circulated a report and documents that it says suggest Iran has been conducting research and procurement that could lead to a nuclear bomb.
Iranian officials insist their nuclear programme is only for energy and research, and call the IAEA evidence a US fabrication.
Meanwhile, Mr Hu said growing economic instability and uncertainty around the globe mean it is more important for China and the United States to increase their cooperation.
The Chinese premier and President Obama spoke at the start of a meeting during an Asia-Pacific economic summit in Hawaii.
Mr Hu said the Asia Pacific region is the most dynamic region of the world and should become a region of active cooperation between the US and China.
Mr Obama said cooperation between the two countries was vital to their prosperity and the prosperity of nations around the globe.
Mr Hu did not address US concerns over intellectual property and China's undervalued currency, which keeps Chinese exports cheaper and US exports to China more expensive.