TEHRAN, Iran — Supreme leader Ayatollah Ali Khamenei said Sunday that attempts to punish Tehran would jeopardize the world's oil supply. He also called Western accusations that Iran is seeking nuclear weapons a "sheer lie."

The implied threat was dismissed by Secretary of State Condoleezza Rice, who said Iran was too dependent on oil revenues to disrupt the flow of crude.

She also put Iran on notice that incentives offered by the West for it to suspend its nuclear program are not open-ended, although she declined to say Tehran had a firm deadline to respond.

Khamenei, who has the final say on all state matters, made his comments in a speech broadcast on state radio.

"If you make any mistake [punish or attack Iran], definitely shipment of energy from this region will be seriously jeopardized," Khamenei said, addressing Western nations.

He said the United States and its allies would be unable to secure oil shipments passing out of the Gulf through the strategic Strait of Hormuz to the Indian Ocean. At its narrowest point, the strait separating Iran from the Arabian peninsula is 44 miles wide.

"You will never be able to protect the energy supply in this region. You will not be able to do it," Khamenei said.

He did not specify how supplies would be disrupted, however, and insisted to the assembled throng that Iran would not be "the initiator of war."

Last week, Rice said the United States was prepared to join the European Union and Germany in negotiations with Iran only if Tehran agreed to stop enriching uranium. The Western nations fear Iran is using what it calls a peaceful civilian nuclear program as a cover to build atomic weapons.

Khamenei said Iran was not a threat to any country. "We have not threatened any neighbor," he said, calling the accusation that Iran is seeking an atom bomb "a sheer lie."

"It's against Islamic teachings," he said.

However, Iranian President Mahmoud Ahmadinejad repeatedly has questioned Israel's right to exist and said in October the Jewish state should be "wiped off the map." Israel is believed to possess the world's sixth-largest nuclear arsenal.

Khamenei's harsh rhetoric came a day after Ahmadinejad said a breakthrough in negotiations was possible. He welcomed the U.S. offer to join talks but rejected preconditions.

Contrary to Khamenei's remarks, other Iranian officials have repeatedly ruled out using oil as a weapon. Iran is the world's fourth-largest oil exporter and has the second-largest reserves in the Organization of Petroleum Exporting Countries.

Iranian political analyst Saeed Leilaz said Khamenei's remarks were more important for what he did not say.

"He didn't close the door for dialogue or understanding with the U.S.," Leilaz said. "Khamenei even didn't close the door for possibility of Iran suspending uranium enrichment. Iran is after maximum concessions from America."