"The European Council calls for de-escalation and maximum restraint, the protection of civilians and civilian infrastructure and full respect of international law by all parties," the leaders of the EU's 27 nations said in written conclusions of a summit in Brussels.
"In this regard, it calls for a moratorium on strikes against energy and water facilities," they said.
The leaders called for reinforcing the bloc's existing Red Sea naval mission Aspides and counter-piracy naval mission Atalanta in the Horn of Africa "with more assets, in line with their respective mandates".
US President Donald Trump has lashed out at allies who have responded cautiously to his demands that they help secure the Strait of Hormuz, the conduit for about a fifth of the world's oil.
In their statement, the European leaders welcomed "the increased efforts announced by Member States, including through strengthened coordination with partners in the region, to ensure freedom of navigation in the Strait of Hormuz, once the conditions are met".
Natural gas prices in Europe surged as much as 35 per cent on Thursday as Iranian and Israeli strikes targeted some of the Middle East's most important gas infrastructure, doing damage that will likely take years to repair.
The strikes on energy facilities since the onset of the US and Israeli war on Iran have brought to life some of the energy industry's worst fears - that a conflict in the region will leave long-term damage and shortages in global energy supplies.
"We are now well on the road to the doomsday gas-crisis scenario," said Saul Kavonic, an energy analyst at MST Financial. "Even once the war ends, the disruption to LNG supply could last for months or even years."
Iran on Thursday struck the Ras Laffan liquefied natural gas facility in Qatar, the world's largest LNG complex, a day after Israel attacked Iran's huge South Pars gas facilities.
The hit on Ras Laffan destroyed two LNG trains that could cause a reduction of around 17 per cent of Qatar's liquefied natural gas exports for between three and five years.
"I never in my wildest dreams would have thought that Qatar would be - Qatar and the region - in such an attack, especially from a brotherly Muslim country in the month of Ramadan, attacking us in this way," QatarEnergy chief executive Saad al-Kaabi told Reuters.
Aerial attacks by Iran have already targeted a refinery in Saudi Arabia, forced the United Arab Emirates to shut gas facilities, and started fires at two Kuwaiti refineries. US President Donald Trump threatened retaliation if they persisted.
Israeli Prime Minister Benjamin Netanyahu said in a call that he would not attack any more Iranian energy facilities, Trump said on Thursday.
Netanyahu confirmed at a press conference the US president had asked him to hold off on further such attacks.
