Earlier Israel said its warplanes carried out raids targeting Iranian military facilities in retaliation for a missile barrage -- further stoking fears of a full-scale regional war.

"The dangerous cycle of attacks and retaliations risks causing a further expansion of the regional conflict," the EU said in a statement.

"While acknowledging Israel's right to self-defence, the EU calls on all parties to exercise utmost restraint to avoid an uncontrollable escalation, which is in no one's interest."

Iran warned it would defend itself after the strikes, which the Israeli military said hit Iranian missile factories and military facilities in several regions, killed two soldiers.

Israel in turn cautioned that Iran would "pay a heavy price" if it responded to the strikes, which it said came in retaliation for Iran's October 1 missile attack, which saw the country launch around 200 ballistic missiles at Israel.

The EU called for calm saying the strikes came amid "severe and growing regional tensions".

"The EU remains fully committed to lowering tensions and contributing to de-escalation and, to this end, remains in close contact with all relevant actors," the 27-nation bloc added.