If you (Washington) make a wrong step over Iran, energy flow in the region will certainly be endangered," Khamenei said in a speech broadcast on state television.

"You (Washington) will be unable to secure the energy flow in this region," he stressed.

Khamenei also declared that Iran would not give up its right to peaceful nuclear energy in the face of "threats and bribes" and praised efforts by Iranian nuclear scientists in developing peaceful nuclear technology.

"We have achieved a lot of scientific goals and this is a resource that our late imam had saved for us," Khamenei said in the speech marking the 17th anniversary of the death of Iran's Islamic revolutionary leader Ayatollah Ruhollah Khomeini. Iran is close to the Hormuz Strait, which is a strategic waterway that controls oceangoing traffic to and from the oil-rich Gulf states.

Iran, a member of the Organization of Petroleum Exporting Countries (OPEC), is the world's fourth largest oil producing country.

Khamenei made the threat one day after Iranian President Mahmoud Ahmadinejad said that Tehran was ready to hold "fair and unconditional" talks with the West over Iran's nuclear issue.

Ahmadinejad also said that Iran would decide, on the basis of Iran's national interests, on a new European proposal aimed to solve the standoff over the nuclear issue.

Foreign ministers of the five permanent members of the UN Security Council--the U.S., France, Britain, Russia and China--plus Germany agreed Thursday upon the European offer of incentives if Iran halts uranium enrichment and punishments if Tehran does not comply.

EU foreign policy chief Javier Solana is expected to convey the offer to Iran soon. No details about the proposal have been unveiled.

Meanwhile, during a phone call with UN Secretary General Kofi Annan on Saturday, Ahmadinejad reasserted that Iran was ready to hold talks on its nuclear program, adding that Iran preferred the negotiations to be held "democratically without any precondition or any threat."

Annan, on his part, said that continued negotiation was the only way to help settle Iran's disputed nuclear issue, according to Iran's state media.

"I understand that Iran is opposing any threat to its national security and I have drawn attention of the U.S. and Europeans to the fact that Iran is right to dismiss any threat concerning the nuclear program," the U.N. chief was quoted as saying.