RIYADH, Saudi Arabia — U.S. Secretary of State Hillary Rodham Clinton made clear Saturday that time is running out for diplomacy with Iran over its disputed nuclear program, saying Tehran’s “window of opportunity” for a peaceful resolution “will not remain open forever.”

She also expressed doubt about whether Iran has any intention of negotiating a solution that satisfies the U.S., Israel and other countries that believe Iran is trying to develop nuclear weapons.

Tehran contends the program is solely for peaceful energy and research purposes.

Her remarks at a security conference in Saudi Arabia follow President Barack Obama’s announcement Friday that the U.S. was moving ahead with penalties aimed at depriving Iran of oil revenue, while also working with Saudi Arabia and other Persian Gulf States to ensure ample global petroleum supplies.

Clinton prodded Gulf governments to develop a coordinated defense strategy against Iranian missiles. With tensions rising in the region, she said American and Gulf militaries should cooperate to improve maritime security as well.