US Secretary of State Mike Pompeo on Saturday blamed Iran and said there was no evidence to suggest the attacks were carried out from Yemen despite the fact they were claimed by Iran-backed Houthi rebels there, Efe news reported.
US President Donald Trump said his country's intelligence had an evidence pointing to a culprit, although he failed to specify who he thought was behind the attack. He said the US was "locked and loaded" and was just waiting for input from Riyadh on how to proceed.
Denying the claims made by the US, Iranian Foreign Minister's spokesman Abbas Mousavi said: "These accusations are unacceptable and completely unfounded."
"The Saudi-led coalition with Western powers has committed extensive war crimes in Yemen and it is natural that the people and the Yemeni Army responds to those," he added.
The Houthis a Shia militia engaged in a protracted civil war against the internationally-recognized Yemeni government, which has the military support of a Saudi-led coalition claimed responsibility for Saturday's bombing by 10 unmanned aircraft of two refineries belonging to Aramco.
On Monday, they warned they could carry out further attacks against the company.
In the wake of the attack, Riyadh dropped its oil output by 50 per cent.
Speaking to the US media, several unnamed intelligence sources said they had evidence suggesting that, contrary to the Houthi claims, Iran had launched a dozen cruise missiles and over 20 unmanned drones from its territory, according to Efe news.
"The war is between the Yemenis and the Saudis and does not have anything to do with the Islamic Republic," Mousavi said, insisting that Tehran's outspoken support for the Houthi rebels was purely political.
Riyadh and Washington have accused Iran of arming the rebel forces.
After the bombing on Saturday, Brent crude, the global gauge of oil prices, jumped 10.5 per cent to $66.56 per barrel after closing at $60.23 on Friday.
Authorities in Saudi Arabia are still investigating the attack and are yet to identify a culprit.
The attack came amid speculation that Trump could meet with Iranian President Hassan Rouhani on the sidelines of the upcoming UN General Assembly set to be held in New York City.
"Saudi Arabia oil supply was attacked. There is reason to believe that we know the culprit, are 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, and under what terms we would proceed!" Trump wrote on his Twitter account.
Tensions between the US and Iran have been simmering since Trump unilaterally abandoned an international nuclear deal in 2018 and re-applied tough sanctions on the Iranian economy.
( With inputs from IANS )