UN Secretary-General Ban Ki-moon has warned Iranian President Mahmoud Ahmadinejad of the dangers of incendiary rhetoric.

The two have met in New York in advance of this week's annual gathering of world leaders at the UN General Assembly.

"The secretary-general drew attention to the potentially harmful consequences of inflammatory rhetoric, counter-rhetoric and threats from various countries in the Middle East," Mr Ban's press office said.

Israeli Prime Minister Benjamin Netanyahu has hinted that Israel could strike Iran's nuclear sites and criticised US President Barack Obama's position that sanctions and diplomacy should be given more time.

Speaking to reporters at the UN general assembly, Iranian President Mahmoud Ahmadinejad said Iran does not take Israel's threats seriously but is prepared to defend itself.

Iran denies that it is seeking nuclear arms and says its atomic work is peaceful, aimed at generating electricity.

"Fundamentally we do not take seriously the threats of the Zionists. ... We have all the defensive means at our disposal and we are ready to defend ourselves," Mr Ahmadinejad said.

"While we are fully ready to defend ourselves, we do not take such threats seriously," he said, speaking through an interpreter.

Amir Ali Hajizadeh, a brigadier general in Iran's Islamic Revolutionary Guard Corps, was quoted yesterday as saying that Iran could launch a pre-emptive strike on Israel if it was sure the Jewish state was preparing to attack it.

"The nuclear issue is not a problem. But the approach of the United States on Iran is important," Mr Ahmadinejad told reporters. "We are ready for dialogue, for a fundamental resolution of the problems" but under conditions that are based on "fairness and mutual respect," he added.

Mr Ahmadinejad also said Israel had "no roots" in the history of the Middle East and represents a disturbance for Iran.

The worsening situation in Syria is also high on the agenda at the General Assembly.

Speaking to reporters in New York, German Foreign Minister Guido Westerwelle said that "to increase pressure and to increase the isolation of the regime of Assad is one of the goals this week".

On Wednesday, Mr Westerwelle will chair a ministerial meeting of the UN Security Council on the Arab Spring at which Syria is expected to be a major theme.

Other diplomats said the furore caused by an anti-Islam film made in California would also be a major issue.

The UN-Arab League mediator in the Syria crisis, Lakhdar Brahimi, will address the Security Council later in a private meeting.