Iran's Supreme Leader Ayatollah Ali Khamenei has warned that his country will retaliate against Western-backed oil sanctions and any threat of attack, after U.S. Defense Secretary Leon Panetta was cited in media reports as saying he fears Israel could attack Iran in the next few months.

A report Thursday in the Washington Post, later backed by other news outlets, said Secretary Panetta fears Israel could attack Iran as early as April, to stop Tehran's progress on a possible nuclear bomb. Panetta was not directly quoted in the report and has not commented on it.

Khamenei's comments came in a speech on state television Friday as he marked the anniversary of the 1979 Islamic Revolution in Iran.

He said sanctions will have no effect on Iran's determination to continue its nuclear program. He also said Iran will back any nation or group that intends to confront Israel.

Israel is among the nations, including the United States, that suspect Iran may be enriching uranium to make nuclear weapons. Israel has not ruled out an attack on Iran's nuclear facilities, while the United States is pushing for increased international sanctions instead.

Iran insists its nuclear activities are only for peaceful purposes.

In retaliation for any further action, Iran has repeatedly threatened to close the Strait of Hormuz, through which much of the world's oil is shipped.