Iran is ready to defend itself against any Israeli attack, an Iranian envoy told the UN General Assembly after Israel's Prime Minister Benjamin Netanyahu threatened to act alone to stop Iran getting a nuclear bomb.

"The Israeli prime minister had better not even think about attacking Iran, let alone planning for that," Khodadad Seifi, a deputy ambassador at Iran's UN mission, told the UN General Assembly.

The diplomat spoke immediately after Netanyahu in the assembly to condemn what he called the Israeli prime minister's "extremely inflammatory" and "saber-rattling" remarks.

The diplomat said Netanyahu should "seriously avoid miscalculation" in the showdown.

"Iran's centuries-old policy of non aggression must not be interpreted as its inability to defend itself.

"Unlike Israel, Iran did not and would not attack any country," he added in the right of reply statement.

Iran's opponents, such as Netanyahu, have accused Iran of leading a charm offensive while pursuing nuclear weapons. Seifi said: "A smile attack is better than a military attack. And indeed, a smile policy is much better than lying."