The tanker is operated as a Panama-flagged vessel, thus he said, "Without doing thorough research, it's hard to find out that it is operated by a Japanese company".
U.S. Defense Secretary Patrick Shanahan said the United States was "planning various contingencies" when asked if more military forces would be sent to the area, but added that the focus was on building an worldwide consensus.
But he emphasized the issue of building consensus.
Saudi Arabia's energy minister Khalid al-Falih said the kingdom was monitoring the situation with "great concern" and called for action to secure maritime traffic, the Saudi SPA news agency said.
"We also need to broaden our support for this worldwide situation", he told reporters.
Nathalie Tocci, a senior adviser to European foreign policy chief Federica Mogherini also rejected the U.S. allegations, saying, "Before we blame someone, we need credible evidence".
Interested in Iran? Add Iran as an interest to stay up to date on the latest Iran news, video, and analysis from ABC News. "This is the same man by the way who refused to condemn Putin after the Salisbury Novichok attacks", he said.
"The secretary of state Pompeo says the US assessment is Iran is responsible for the attack on two oil tankers in the Gulf of Oman".
The crew of the Kokuka Courageous saw a "flying object" before a second blast on board, the operator's head said Friday.
The first ship hit was the Front Altair, owned by Frontline, a Norwegian company. "To put a bomb at the side of the boat is not something we are considering".
Iran has rejected the United States accusation against it as "baseless".
When asked how the United States will stop Iran, he replied: "We will see".
UN Secretary-General Antonio Guterres told the UN Security Council on Thursday the world could not afford "a major confrontation in the Gulf region".More news: High times in ancient China revealed in funerary cannabis discovery
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US Defence Secretary Patrick Shanahan said the US would be sharing intelligence to try to "build global consensus to this worldwide problem".
"I don't think they've talked the same way when President Obama signed agreement, they were saying death to America, they were having good time at his expense and he's given them 150 billion in cash, cash, nobody ever heard of a thing like that and all of that money and screaming death to America, they haven't screamed death to America lately", Trump said.
"We strongly condemn the attacks no matter who is behind them", the ministry said in a statement.
The two oil tankers were attacked at dawn on Thursday about 40 kilometres (25 miles) off the southern coast of Iran.
The owner of the Japanese tanker, has meanwhile claimed that the United States has provided "false information" about what happened.
The Iranian mission to the United Nations rejected the US' claim.
Iran denies involvement in the incidents, while its foreign minister Zarif said on Twitter that the U.S.
Justin Bronk, a combat technology specialist at the Royal United Services Institute, said the patrol boat shown in the U.S. video was known to be the kind used by the IRGC. He also said any move to close the Strait of Hormuz would not last long.
"On the other hand, you could argue that they were keen to pick up an unexploded mine to avoid it linking back to them. I guess they didn't want the evidence left behind".
"The time is now for the United States to exert worldwide leadership", Sanders continued, "and bring the countries in the region together to forge a diplomatic solution to the growing tensions".
The Japanese owner of the Kokuka Courageous, one of the vessels attacked near the strategic Strait of Hormuz in the Gulf of Oman on June 13, said their sailors saw "flying objects" immediately before the attacks.
The Strait of Hormuz provides the only sea passage from the Gulf to the open ocean and is one of the world's most important sea lanes.