By Francois Murphy

VIENNA (Reuters) -U.N. nuclear watchdog chief Rafael Grossi said on Friday he was ready to travel to Iran to assess the situation there after Israel carried out widespread military strikes that hit the sprawling nuclear complex at Natanz.

In a statement to a meeting of the International Atomic Energy Agency's Board of Governors, Grossi said the other main enrichment centre in Iran, Fordow, was not hit and neither was another nuclear facility in Esfahan, citing Iranian authorities.

There are no elevated radiation levels at Natanz, he added.

"I call on all parties to exercise maximum restraint to avoid further escalation. I reiterate that any military action that jeopardizes the safety and security of nuclear facilities risks grave consequences for the people of Iran, the region, and beyond," Grossi said in his statement.

"I have indicated to the respective authorities my readiness to travel at the earliest to assess the situation and ensure safety, security and non-proliferation in Iran."

He did not say what the extent of the damage at Natanz was or what parts of the site were hit. The site includes a vast underground uranium enrichment plant and a smaller, above-ground pilot enrichment plant.

Iran is enriching to up to 60% purity, close to the roughly 90% of weapons grade, at the pilot plant, but it is producing smaller quantities of that material there than at Fordow, a site dug into a mountain that military experts have said would be difficult for Israel to destroy through bombardment.

"Despite the current military actions and heightened tensions, it is clear that the only sustainable path forward - for Iran, for Israel, the entire region, and the international community - is one grounded in dialogue and diplomacy to ensure peace, stability, and cooperation," Grossi said.

(Reporting by Francois MurphyEditing by Dave Graham)