Trump told reporters that Iran was responsible for the Yemeni attacks that targeted the Saudi oil giant, according to Al-Jazeera.
"It is certainly looking that way at this moment," Trump told reporters when asked if he believes Iran carried out the attack but added that Washington still wanted more proof.
"We want to find definitively who did this," Trump told reporters in the Oval Office.
He also boasted that the US has 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 denied the allegations.
The attacks took place early on Saturday on two major oil facilities in Saudi Arabia.