European leaders are voicing alarm over the military attacks launched overnight between Israel and Iran and calling for immediate de-escalation to avoid an all-out war that could spiral across the Middle East and beyond.

Operation Rising Lion, involving more than 200 Israeli jets, targeted a facility in Natanz and the capital overnight — sparking alarm at the potential for an all-out war.

The two leaders spoke on Friday evening, as western nations began a diplomatic flurry to calm the burgeoning conflict, which started with early morning Israeli strikes on Iranian nuclear bases.

But Trump also kept the door open for negotiations on Tehran's nuclear program, as the president who boasted he had "no wars" in his first term tries to avoid getting dragged into one in his second.