Guterres underlined the need for an investigation to establish the facts about the attacks, adding that he believed only the Security Council could order a UN inquiry, Presstv Reported.
“It’s very important to know the truth and it’s very important that responsibilities are clarified. Obviously that can only be done if there is an independent entity that verifies those facts,” he said.
The Japanese-owned Kokuka Courageous and Norwegian-owned Front Altair oil tankers were struck by explosions near the strategic Strait of Hormuz waterway in the early hours of Thursday.
They were hit while sailing in the Sea of Oman after leaving ports in Saudi Arabia and the United Arab Emirates.
Japan’s government said both vessels were carrying “Japanese-related” cargo. The attacks came as Japanese PM Shinzo Abe was meeting with Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei in Tehran.
The cause of the attack is not yet known, but the Japanese shipping company has said two "flying objects" attacked its tanker in the Oman Sea, contradicting the US account that mines had hit the vessels.
A few hours after Thursday's attacks, US Secretary of State Mike Pompeo offhandedly blamed Iran for the attack without providing evidence. US President Donald Trump also claimed that the incident had Iran "written all over it"
The accusation was further echoed by British Foreign Secretary Jeremy Hunt, who blamed Iran and Iran's Islamic Revolution Guards Corps (IRGC) for the attacks.
On Thursday, the US Central Command (CENTCOM) released a grainy footage purportedly showing "an IRGC Gashti Class patrol boat ... removing [an] unexploded limpet mine" from the side of the Japanese ship following the blasts.
Iran was the first country to respond to a distress call and rush to the assistance of the oil tankers, transferring all their 44 crew members to its southern shores.
“The US government has turned into a serious threat to the stability of the region and the world over the past two years through misusing its economic, financial and military capacities,” Iran's President Hassan Rouhani said on Friday.
Foreign Minister Mohammad Javad Zarif also tweeted that the US had “immediately jumped to make allegations against Iran without a shred of factual or circumstantial evidence."
He said the US allegations against Iran over the tanker attacks were part of “sabotage diplomacy” adopted by the so-called B-Team.
The B-Team refers to US national security adviser John Bolton, Abu Dhabi Crown Prince Mohammed bin Zayed Al Nahyan, Israeli Prime Minister Benjamin Netanyahu and Saudi Crown Prince Mohammed bin Salman.
Iran also warned the US to stop playing a blame game through "suspicious" attacks on oil tankers in the Middle East, describing the American behavior as "worrying".
Iran diplomat: Accusers 'have the main role'
On Thursday, Iran's deputy ambassador to the UN Es'haq Al-e Habib brushed aside the US claims that Tehran was responsible for the attacks in the Sea of Oman.
"Strongly we are rejecting any accusation of Iran," he said. "Definitely, those that accuse Iran have the main role in creating those incidents and it could be the United States itself."
In an indirect reference to Israel and Saudi Arabia, the Iranian diplomat noted that the two regimes "are looking for more tensions" in the Persian Gulf region and that Washington is a staunch backer of them.
The incident in the Sea of Oman "happened at the same, exactly at the same time that the prime minister of Japan was in Iran and meeting our leaders, and it shows that these are orders that are behind this incident, and the previous one," he added.
Oil prices jumped as much as 4 percent following Thursday's incident.
The blasts came a month after mysterious attacks on four oil tankers -- an Emirati, a Norwegian and two Saudi vessels -- off the coast of Fujairah in the UAE on May 12.