US President Donald Trump said on Monday that it looked like Iran was responsible for attacks over the weekend on Saudi Arabian oil plants, but he wants to avoid war. 

"It is certainly looking that way at this moment," Trump told reporters when asked if he believes Iran carried out the attack. 

Without providing evidence, Trump said "we pretty much already know" and "certainly it would look to most like it was Iran" but that Washington still wanted more proof.

"We want to find definitively who did this," Trump told reporters in the Oval Office, where he was meeting with Bahrain's Crown Prince Salman bin Hamad bin Isa Al Khalifa. "You're going to find out in great detail in the near future," he said. "We have the exact location of just about everything.

"With all that being said, we'd certainly like to avoid" war, he said. "I don't want war with anybody but we're prepared more than anybody."

Washington has blamed Tehran for the attacks, which cut five percent of world crude oil production. Iran has rejected the allegations. 

The attacks took place early on Saturday on two major oil facilities in Saudi Arabia.

Yemen's Houthi rebels, who have been locked in a war with a Saudi-UAE-led coalition since 2015, claimed responsibility for the attacks, warning Saudi Arabia that their targets "will keep expanding".

A Saudi military spokesman on Monday said initial investigations show Iranian weapons were used in the weekend attacks.

In denying it was behind the attacks, Iran has said such allegations were meant to justify actions against it.

US Secretary of Defense Mark Esper said earlier on Monday the attacks were "unprecedented" and the US, along with its allies, was working to defend the "international rules-based order that is being undermined by Iran."

In a phone call to Saudi Arabia's Crown Prince Mohammed bin Salman, Esper said the US was studying all available options in how it will respond to the attacks.

Esper affirmed the US's full support for Saudi Arabia following the attacks, state news agency SPA reported. 

Trump on Sunday had said that the US is "locked and loaded depending on verification, but are waiting to hear from the Kingdom as to who they believe was the cause of this attack". 

Al Jazeera