U.S. Secretary of State Condoleezza Rice says she is confident the United States and its allies will reach agreement on how to pressure Iran to abandon sensitive nuclear activities.

Ms. Rice spoke after a meeting with Caribbean foreign ministers. She said diplomacy takes time.

The United Nations Security Council had planned to discuss Iran Tuesday. But that session was postponed to give the five permanent Council members and Germany more time to agree on how to press Iran to suspend uranium enrichment activities and comply with international standards.

In other developments, Iran's supreme leader, Ayatollah Ali Khamenei, says he approves of talks between Iran and the United States on stabilizing Iraq. The U.S. and Iran both say any meetings they may have will focus only on ways to bring stability to Iraq.

President Bush said Tuesday Iran must understand that it cannot be allowed to make nuclear weapons, in the interest of world security.

Ayatollah Khamenei delivered his speech several hours after Mr. Bush's comments at a news conference in Washington. The Iranian leader said Iran will not agree to any U.N. Security Council ruling on its nuclear program that goes against Tehran's interests.

The United States suspects Iran is seeking to build a nuclear weapon. Tehran denies the charge.