China said Friday it was "deeply concerned" over Israeli strikes on Iran — including nuclear and military sites — condemning "violations" of the country's sovereignty and offering to help ease tensions.

"The Chinese side... is deeply worried about the severe consequences that such actions might bring," Foreign Ministry spokesman Lin Jian said.

"The Chinese side calls on relevant parties to take actions that promote regional peace and stability and to avoid further escalation of tensions," Mr Lin said.

Israel pounded Iran in a series of air raids on Friday, striking 100 targets and killing the armed forces' chief of staff, the head of Iran's Revolutionary Guards and top nuclear scientists.

Iran's supreme leader Ayatollah Ali Khamenei warned Israel it faced a "bitter and painful" fate over the attacks.