U.S. Secretary of State Condoleezza Rice says the U.N. Security Council must be ready to take action against Iran if it fails to end sensitive nuclear activities.

In Bulgaria for a NATO meeting Thursday, Rice said it is highly unlikely that Iran will comply with Council demands to end uranium enrichment by Friday. Rice said the United States believes the Security Council has to act to remain credible.

Earlier, Iranian President Mahmoud Ahmadinejad vowed his country would not give in to pressures to curb its nuclear program. Also Thursday Russian President Vladimir Putin said after a meeting with German Chancellor Angela Merkel on Thursday that the International Atomic Energy Agency (IAEA) should deal with Iran, and not refer it to the Security Council where Iran could face sanctions.

The IAEA is scheduled to present a report to the U.N. Security Council Friday on Iran's compliance with demands to stop sensitive nuclear work.

Iranian nuclear chief Gholamreza Aghazadeh met with IAEA head Mohamed ElBaradei in Vienna on Wednesday for last-minute talks on the issue. No breakthrough was reported.