Saudi Arabia says oil infrastructure sites belonging to the country's state-run oil company Aramco have been targeted and that at least one of the attacks was carried out by drone strikes.
However, neither Saudi Arabia nor the UAE said who was or is most likely to have been behind the attack.
The 1,200-kilometre (750-mile) pipeline carries crude from Saudi Arabia's main eastern oil fields to the Red Sea port city of Yanbu in the west.
Fox News quoted a source on Monday night who said a US military team has examined the four commercial vessels damaged by explosions off the coast of the UAE on Sunday and concluded agents of Iran or its proxy forces attacked them.
Saudi Energy Minister Khalid al-Falih called the attack, which came on the heels of reported damage to Saudi and UAE-flagged tankers in the Gulf, "an act of terrorism and sabotage" against the global oil flow.
Gulf officials have characterised the damage to the tankers as a sabotage.
An American military team assessing blasts that damaged four commercial ships off the coast of the United Arab Emirates (UAE) Sunday has blamed Iran or Iranian-backed proxies using explosive charges, a source told Fox News on Monday evening. "It's not in [Iran's] interest, it's not in our interest, it's not in Saudi Arabia's interest to have a conflict".
Saudi Arabia has been leading a Sunni Arab military coalition against the Yemeni Shiite Houthi rebels since March 2015 to support the internationally-recognized government of President Abd-Rabbu Mansour Hadi who was forced into exile in Riyadh, the Saudi capital.
The team of United States military experts was sent to investigate the damages at the request of the UAE, but American officials have not provided any details about what exactly happened or any proof about the possible Iranian involvement in the alleged sabotage incidents.
"There are a number of reports carrying one or two U.S. officials saying the U.S. suspects Iran is behind this, but it's all based on assumptions". A U.S. official, who spoke to the AP on condition of anonymity to discuss the ongoing investigation, said all the ships sustained similar damage.
Iraqi Prime Minister Adel Abdul Mahdi said on Tuesday that neither the United States nor Iran wanted war, and Iraq was in contact with both, state news agency INA reported. According to him, the attack "did not lead to any casualties or an oil spill but damaged the structures of the two vessels.".
Washington suspects Iran but Tehran has denied any involvement.
"God willing we will pass this hard period with glory and our heads held high, and defeat the enemy", Rouhani said at a late night meeting with clerics.
The U.S. has sent forces, including an aircraft carrier and B-52 bombers, to the Middle East in a move that officials said was to counter "clear indications" of threats from Iran to American forces in the region.
A fifth of global oil consumption passes through the Strait of Hormuz from Middle East crude producers to markets in Asia, Europe, North America and beyond.