A top advisor to Iran's supreme leader Ayatollah Ali Khamenei said Monday that the recent letter of the United States to the Islamic republic's supreme leader has nothing new, the semi-official Fars news agency reported.

Advisor to Iran's supreme leader Ayatollah Ali Khamenei?[File photo]

Asked by the reporters about the content of the U.S. letter, Ali-Abar Velayati said "this letter bears no new words."

Velayati did not elaborate further on the content of the letter, said Fars.

Iranian Foreign Ministry spokesman Ramin Mehmanparast confirmed on Sunday that Iran had received a letter from the United States over the Strait of Hormuz.

Mehmanparast said the U.S. administration had delivered three copies of the letter to Iran through different channels, including via Iraqi President Jalal Talabani, the U.S. representative to the United Nations Susan Rice, the Iranian representative to the United Nations Mohammad Khazaei, and Swiss Ambassador to Tehran Livia Leu Agosti.

"The Islamic republic is studying the letter and will respond to it if it is necessary," Mehmanparast said.

Mehmanparast did not elaborate on the content of the U.S. letter either.

The New York Times reported Friday that the United States had used a secret channel to send a letter to Khamenei over Iran's threats of closing the strategic waterway of Hormuz Strait. The report said the United States warned in the letter that closing the strait would be crossing a "red line" and would provoke a response.

Some Iranian government and military officials have threatened that Iran will close Hormuz Strait if its oil exports are sanctioned by the West.

After the International Atomic Energy Agency (IAEA) issued a report on Iran's nuclear program in November, the United States, Britain and Canada announced new sanctions against Tehran.

Also, the United States and its Western allies are considering sanctions on Iran's oil exports for its insistence to pursue the controversial nuclear program.

On the potential embargo on Iran's oil exports, Velayati said Monday that "Oil is not a commodity to be able to put sanctions on. It can be sold in a number of ways and the Islamic republic can sell its oil easily," according to Fars.

"As usual, the demand for Iran's oil is more than the country's outputs," he was quoted as saying.

On Monday, a senior Iranian lawmaker, Esmaeil Kowsari, said that the recent U.S. letter to Iran about the Strait of Hormuz showed the effectiveness of the country's military might, the local satellite Press TV reported.

Kowsari reiterated that if sanctions against Iran came into effect, the Islamic republic would definitely prevent oil exports through the Strait of Hormuz, said the report.

Deputy Chairman of Joint Chief of Staff of Iran's Armed Forces Brigadier General Massoud Jazayeri said Monday the United States could not hinder Iran's efforts to shut down the strategic strait if Tehran deemed it necessary, Press TV reported.

"Regardless of their publicity campaigns and propaganda efforts, the Americans are incapable of confronting Iranian actions in a number of spheres, including the potential plan (by Iran) to shut down the Strait of Hormuz," Jazayeri was quoted as saying.

The principal objective of Iran in the region is to defuse tensions, Jazayeri said, adding that however should the country's national interests came under threat, Iran's armed forces would utilize their defensive capabilities to defend the country's sovereignty.

On Sunday, Iran's OPEC Governor Mohammad-Ali Khatibi warned against any crude boosts by the Persian Gulf states to compensate for the potential Western embargo on Iran's oil exports.

"If our southern neighbors collaborate with the adventurous states by substituting their oil for Iran's oil," Tehran will consider such a "green light" to the West as an unfriendly gesture, Khatibi said.

If the Gulf countries were prudent enough to announce that they would not participate in an oil embargo against Iran, the "adventurous" Western countries will be dissuaded from imposing oil sanctions against Iran, he added.

Any attempt to substitute Iran's crude is not a mere business initiative and it would mean entering a "very dangerous political game," he said.

Israeli Prime Minister Benjamin Netanyahu said Monday that the current international sanctions imposed on Iran were not effective and must be tightened.

"As long as there will not be effective sanctions on Iran's central bank and oil industry, there won't be any effect on its nuclear program," Netanyahu said during a discussion in the Knesset's defense and foreign affairs committee.