The United States is concerned about threats from Iran against Saudi Arabia and will not hesitate to respond if necessary, a White House spokesperson said on Tuesday.
The Wall Street Journal reported that Saudi Arabia had shared intelligence with the US, warning of an imminent attack from Iran on targets in the Kingdom.
The US, Saudi Arabia and other countries in the Middle East are on an elevated alert level without providing further details, it added.
Saudi officials said Iran is poised to carry out attacks on the Kingdom and Erbil, Iraq, to distract attention from domestic protests that have swept the country since September.
"We are concerned about the threat picture, and we remain in constant contact through military and intelligence channels with the Saudis," said a National Security Council spokesperson.
"We will not hesitate to act in defense of our interests and partners in the region."
Head of Iran's National Security and Foreign Policy Committee MP Vahid Jalalzadeh had said if Saudi Arabia did not stop supporting the protests, it would "face countermeasures" from Tehran.
Jalalzadeh revealed that Tehran had sent messages to Riyadh "through friendly countries," adding that Saudi Arabia “should stop supporting the rioters”.
Iran's Intelligence Ministry and the Intelligence Organization of the Revolutionary Guard accused on Friday Saudi Arabia, the US, the UK, and Israel of supporting the protests.
Meanwhile, the US and Albania will hold an informal UN Security Council gathering on Wednesday, according to a note outlining the event to highlight the ongoing repression of women and girls in Iran.
The US mission said Wednesday's meeting aims to "highlight the ongoing repression of women and girls and members of religious and ethnic minority groups in Iran."
"It will identify opportunities to promote credible, independent investigations into the Iranian government's human rights violations and abuses."
Iranian Nobel Peace Prize laureate Shirin Ebadi and Iranian-born actress and activist Nazanin Boniadi are set to speak before the meeting.
Tehran urged countries not to attend the Washington-organized meeting.
In a letter to the UN members, Iran's UN ambassador and permanent representative Amir Saeed Iravani said the US has no true and genuine concern about the human rights situation in Iran or elsewhere.
He described the protests as an internal issue, saying it would be "counterproductive to the promotion of human rights" if the UN Security Council discussed the issue.
"The United States lacks the political, moral, and legal qualifications to hold such a meeting, distorting the basic principles of human rights," Iravani wrote.
He questioned the US commitment to defending Iranian women and "strongly urged" UN member states to disassociate themselves from and "explicitly object to such reckless and dangerous practices through which the US attempts to create such a dangerous precedent and politicize human rights issues to achieve its political agenda."
Meanwhile, supporters of the Iranian regime held a sit-in outside the German embassy in Tehran to denounce Berlin's alleged role in fueling the protests.
Germany had recently issued a strongly-worded statement criticizing the suppression of protesters in Iran.
German Foreign Minister Annalena Baerbock condemned the attack on a protest rally in front of the Iranian embassy in Berlin and again sharply criticized the Iranian government.
Speaking from the Uzbek capital, Baerbock said it is wrong to believe that protesters can be intimidated in Germany, adding that the rule of law will be applied.
She explained that any threat to freedom of expression would not be tolerated.
Unknown assailants attacked a bus carrying a mobile home near the Iranian embassy, which is used as a protest headquarters.
According to the police, four bus passengers fought with two masked men, injuring three. It is believed that the suspects fled by car after the attack.
