WASHINGTON — Admiral Mike Mullen, the chairman of the Joint Chiefs of Staff, said yesterday that the US military has a plan to attack Iran, although he thinks such a strike is an undesirable option.

Mullen has often warned that a military strike on Iran would have serious and unpredictable ripple effects around the Middle East. At the same time, he says the risk of Iran developing a nuclear weapon is unacceptable.

Mullen would not say which risk he thinks is worse, but he said in an interview on NBC’s “Meet the Press’’ that a military strike remains an option. He did not elaborate on the plan.

The Iranian news agency IRNA quoted Revolutionary Guard deputy chief Yadollah Javani as saying that security in the Persian Gulf would be jeopardized “if Americans commit the slightest mistake.’’

“The Persian Gulf is a strategic region,’’ Javani said. “If the security of this region is endangered, they will suffer losses, too, and our response will be firm.’’

Iran repeatedly has threatened to target the heart of Tel Aviv, the second-largest city in Israel, should the United States or Israel take military action against it.

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