TEHRAN President Mahmoud Ahmadinejad said on Thursday Iran's "enemies" would never succeed in stopping its nuclear activities, the official IRNA news agency reported.
EU foreign policy chief Javier Solana handed Iran an offer on June 14 of trade and other benefits designed to persuade Tehran to curb its nuclear work and end a row that has helped push oil prices to record highs.
"On the nuclear issue ... the enemies were not able to stop our nation and will never succeed in stopping our program," Ahmadinejad said in a speech in the western city of Kermanshah.
Iranian officials usually refer to the United States and its European allies as enemies. The proposals submitted by Solana two weeks ago were prepared by the United States, Russia, China, Britain, Germany and France.
Tehran said on Tuesday that new punitive measures imposed on it this week by the 27-nation European Union over its nuclear plans could damage diplomatic efforts to resolve the dispute.
Solana said on Wednesday western powers will continue a twin-track policy of sanctions and diplomacy towards Iran over its nuclear program.
Tehran has so far refused to suspend its sensitive nuclear work and has warned major powers pressuring Iran could backfire.
"Even if they succeed to close all doors on Iran, the Iranian nation will become more determined to continue its nuclear path," Ahmadinejad said.
Western powers suspect Iran, the world's fourth-largest oil exporter, wants to make nuclear arms but Tehran denies this.
The stand-off has sparked fears of a military confrontation that would disrupt oil supplies from the Gulf. Last week a report said Israel had practiced for a possible strike against Iran's nuclear facilities.
Washington says it is focusing on diplomatic pressure to thwart Iranian nuclear work but has not ruled out military action if that were to fail.
"These bullying powers ... should know that threats and pressure will not save them from us," Ahmadinejad said.
Iran has repeatedly ruled out suspending enrichment, which can have both civilian and military uses. Their refusal to do so has drawn three rounds of limited U.N. sanctions since 2006.
(Additional reporting by Zahra Hosseinian, Writing by Parisa Hafezi, Editing by Dominic Evans and Richard Meares)