The UK will work its international partners "to forge the widest and most effective response" to the drone attacks on Saudi Arabia's oil facilities.
British Foreign Minister Dominic Raab said on Monday he had spoken with his equivalent in the kingdom as well as ministers in France, Germany and the US in conversations where he condemned the attack.
EU nations stressed the need to establish the source of the attacks, which they called a "wanton violation" of international law.
As President Donald Trump declared the US was "locked and loaded" for a response to the Saudi Arabian losses, the Europeans were keen not to get ahead of the investigations led by Riyadh.
US officials have pinned the blame on Iran, dismissing claims the attack was launched from Yemen.
German Foreign Minister Heiko Maas said his officials were working with partners to find out who had carried out the attacks.
"At the moment we're analysing, along with our partners, who is responsible for this attack and how it could happen," Mr Maas said.
France was convening a meeting to breathe new life into a proposed European naval contribution to protect merchant shipping in the Straits of Hormuz and around the Gulf.
Earlier on Monday Mr Raab appeared to pull back from earlier remarks that blamed Yemen's Houthi militias.
"In terms of who is responsible, the picture is not entirely clear," he said. "I want to have a very clear picture, which we will be having shortly.
"This was a very serious attack on Saudi Arabia and the oil installations and it has implications for global oil markets and supply."
Karen Pierce, the British ambassador to the UN, said Britain was "still assessing what happened and who was responsible for the attacks.
"These were reckless," Ms Pierce said. "They were despicable. They are totally unjustifiable. It is only sheer luck that no one was killed and not by any design of the perpetrators.
"Threatening civilian areas and commercial infrastructure is a violation of international law, as well as being dangerous and provocative.
"At the moment, we’re still assessing what happened and who is responsible for the attacks. Once this has been established, we will discuss with our partners how to proceed in a responsible manner."
The statements took a different tone from that given by London's Foreign Office 24 hours earlier, which tied the attacks on the Aramco plants to Yemen.
"Threatening civilian areas and commercial infrastructure is dangerous, provocative and completely unacceptable," the office said.
"This escalation also undermines UN-led efforts to end the conflict in Yemen. We call on the Houthis to immediately cease such attacks.
"The UK remains committed to supporting the security of Saudi Arabia and to achieving a political solution to the devastating conflict in Yemen."
Alarmed by the double-digit rise in the crude oil prices, German politicians put pressure on Mr Maas to take a higher profile role in addressing the regional tension.
Johann Wadephul, a conservative MP in the governing coalition, warned that the fragile security situation could deteriorate into new conflicts.
"This would have catastrophic consequences for stability and peace in the region, with global implications." Mr Wadephul said.
As a member of the UN Security Council, Germany has taken on a higher profile in foreign affairs, he said adding Berlin must demand restraint from Tehran.
"We Europeans must make clear to Iran that we expect it adheres in words and deeds to the highest international standards and respects the security of its neighbours," Mr Wadephul said.
Meanwhile in Paris, Defence Ministry officials were locked in talks with those from Italy, Denmark, Spain, Norway, Belgium and Sweden about assembling a European-led naval mission.
"It will be with European partners, who are interested in a European mission that doesn't give the impression of being a coalition against Iran," a French official said last week.