"Iran leaves the international community little choice but to impose greater costs for its provocative steps. Together, we are encouraging Iran to reconsider its dangerous policy decisions," Clinton said in a speech prepared for delivery in the Qatari capital.
Clinton, on a visit to the Gulf, is seeking to enlist more Arab diplomatic pressure on Iran to curb its nuclear ambitions and to win greater Arab support to revive frozen Israel-Palestinian peace talks, U.S. officials said.
"We are now working actively with our regional and international partners, in the context of our dual track approach, to prepare and implement new measures to convince Iran to change its course," Clinton said, speaking at a U.S.-Islamic World Forum in Doha. She is also due to visit Saudi Arabia.
U.S. President Barack Obama has made little headway in his effort to restart peace talks or persuade Iran to rein in a civil nuclear program which the West, as well as many Arab states, suspect is a cover to develop atomic weapons.
The United States is leading a push for the U.N. Security Council to impose a fourth round of sanctions on Iran, which says its nuclear program is to generate electricity so it can export more of its valuable oil and gas.
The U.S. officials have hinted that one way Saudi Arabia could help diplomatically would be to offer China guarantees it would meet Chinese oil requirements, a step that might ease Beijing's reluctance to impose further sanctions on Iran.
China, which wields a veto on the Security Council, has lucrative commercial relationships with Iran and, along with Russia, has worked to dilute previous sanctions resolutions.
(Reporting by Arshad Mohammed and Regan E. Doherty; Writing by Cynthia Johnston)
