Colonel Turki al-Malki said initial investigations show the strikes were not launched from Yemen, as the Iran-backed Houthi rebels there have claimed, and were carried out using weapons manufactured by Tehran.
He did not say what evidence Saudi Arabia has uncovered directly linking Iran to the strikes, but promised it would be made public when the probe has finished.
However, the US is convinced that Iran is to blame.
Saudi Arabia's Colonel Turki al-Malki said drone strikes against two of his country's oil facilities at the weekend did not come from Yemen, and pointed the finger directly at Tehran
The Abqaiq oil processing facility (pictured on fire) and Khurais oil field in Saudi Arabia were both rocked by explosions Sunday which cut off 5 per cent of the world's supplies
Donald Trump tweeted Sunday to say that US is 'locked and loaded depending on verification', suggesting he was waiting for Riyadh's confirmation before acting
Tehran has denied any responsibility for the attacks, which have cut Saudi Arabia's oil exports in half and reduced global output by 5 per cent, saying all accusations to the contrary are 'baseless'.
However, a spokesman for the Islamic Revolutionary Guard's aerospace force said the country stood ready for a 'full-fledged war' with America, should they attack.
A senior US official who spoke to ABC Sunday said Iran had launched a dozen cruise missiles and 20 drones from its territory at the world's largest refinery at Abqaiq, and the Khurais oil field.
The official said Trump is 'fully aware' that Iran is responsible, but wanted the Saudis to request US assistance before acting.
The Trump administration also released black and white satellite images overnight which it said showed 17 impact sites at the Saudi facilities, which it said faced towards the north and northwest, towards Iran and Iraq.
However, Houthi rebels, who have been fighting against a Saudi-led coalition in Yemen since 2015, continued to claim responsibility for the blasts on Monday.
'We assure the Saudi regime that our long hand can reach any place we want at any time we choose,' Houthi military spokesman Brigadier Yahya Saree said.
While the Houthis have used drones to attack Saudi oil infrastructure in recent months, the blasts have been centred around the border area and have shown a low level of sophistication when compared with Saturday's bombing.
The Trump administration released satellite photos on Sunday which it said shows damage to the Saudi oil refinery at Abqaiq on the north or northwest side of the buildings, which would be consistent with an attack from Iran or Iraq
An overview of the Abaqaiq oil processing facility before the attacks took place
This image shows damage to the infrastructure at Saudi Aramco's Khurais oil field, which the Trump administration said also shows an attack from the north
A pre-strike overview at Saudi Aramco's Khurais oil field
Abqaiq and Khurais are also located close to the Persian Gulf, away from Yemen, making Iran or Iraq a more-likely point of origin.
Secretary of State Mike Pompeo has led calls for Tehran to be held responsible for the bombing, tweeting on Saturday: 'Iran has now launched an unprecedented attack on the world's energy supply.
'There is no evidence the attacks came from Yemen.'
On Monday, US Energy Secretary Rick Perry unequivocally blamed Iran, describing the drone strikes as: 'Iran's attack on the Kingdom of Saudi Arabia.
Perry said the behaviour is 'unacceptable' and that Iran 'must be held responsible.'
Germany and the UK have both condemned the attack, but said they are waiting for further information to become available before deciding who is responsible.
China, a major importer of Saudi oil, and Russia, a close ally of Iran, have both urged restraint in responding to the attack, though did not rule out Iranian responsibility.
The tensions have led to fears that action on any side could rapidly escalate a confrontation that has been raging just below the surface in the wider Persian Gulf in recent months.
Just last week there were hopes of deescalation following the departure of National Security Adviser John Bolton and the suggestion of talks between Trump and Hassan Rouhani on the sidelines of an upcoming UN summit.
But Washington has now rubbished the idea of talks and put the option of military action firmly back on the table.
It comes after a summer which saw attacks on oil tankers that Washington blames on Tehran, at least one suspected Israeli strike on Shiite forces in Iraq, and the downing of a US military surveillance drone by Iran.
Those tensions have increased ever since Mr Trump pulled the US out of Iran's 2015 agreement with world powers that curtailed its nuclear activities and the US re-imposed sanctions on the country that sent its economy into freefall.
Benchmark Brent crude gained nearly 20 per cent in the first moments of trading Monday before settling down to over 10 per cent higher as trading continued.
That spike represented the biggest percentage value jump in Brent crude since the run-up to the 1991 Gulf War that saw a US-led coalition expel Iraqi dictator Saddam Hussein's forces from Kuwait.
The attack halted production of 5.7 million barrels of crude a day, more than half of Saudi Arabia's global daily exports and more than 5% of the world's daily crude oil production. Most of that output goes to Asia.
At 5.7 million barrels of crude oil a day, the Saudi disruption would be the greatest on record for world markets, according to figures from the Paris-based International Energy Agency (IEA).
It just edges out the 5.6 million-barrels-a-day disruption around the time of Iran's 1979 Islamic Revolution, according to the IEA.
Saudi Arabia has pledged that its stockpiles would keep global markets supplied as it rushes to repair damage at the Abqaiq facility and its Khurais oil field.
However, Saudi Aramco has not responded publicly to questions about its facilities.
Yemen's Houthi rebels, who have been targeted by a Saudi-led coalition since March 2015 in a vicious war in the Arab world's poorest country, maintain they launched 10 drones that caused the extensive damage.
Iraqi premier Adel Abdel-Mahdi said he received a call on Monday from US Secretary of State Mike Pompeo, who confirmed that the attack did not come from Iraq.
The State Department did not immediately acknowledge what was discussed.
Iranian Foreign Ministry spokesman Abbas Mousavi again denied the US claims on Monday, telling journalists the accusation was 'condemned, unacceptable and categorically baseless'.