The US embassy alerted its citizens in the Kingdom to take precautions in a statement published on its website.
— U.S. Embassy Riyadh (@USEmbassyRiyadh) March 14, 2015
In the statement, the embassy said consular services have been cancelled in Riyadh, Jeddah and Dhahran between 15-16 March, and telephone lines will remain closed over these two days.
"All U.S. citizens are encouraged to be aware of their surroundings, and take extra precautions when travelling throughout the country," read the embassy's statement.
"The Department of State urges U.S. citizens to carefully consider the risks of traveling to Saudi Arabia and limit non-essential travel within the country."
The move follows the embassy's warning on Friday (13 March) saying Western oil workers risk being attacked or kidnapped by "terrorist" groups.
The source of the threats and details on the planned attacks were not identified by the embassy.
Foreigners have come under various attacks in Saudi Arabia in what is alleged to be the workings of al-Qaeda-linked militants hoping to destabilize the Western-allied monarchy.
Last month, US defence contractor Vinnell Arabia said two of their American employees were shot at in the Eastern Province.
Last October, another Vinnell employee was shot dead at a gas station in Riyadh, reported AFP News. Saudi authorities have maintained the attack was not "terrorist-related".
In another attack, a Canadian was stabbed and wounded at a mall on Saudi Arabia's Gulf coast.
Saudi Arabia has also blamed IS-linked suspects for an attack on several members of the Shiite community in the Eastern Province last November.
IS has called on jihadi supporters worldwide to attack westerners "wherever they can be found."
"At this point of the crusade against the Islamic State, it is very important that attacks take place in every country that has entered into the alliance against the Islamic State, especially the US, [the] UK, France, Australia and Germany," read an article in IS's official magazine.
"Every Muslim should get out of his house, find a crusader and kill him ... And the Islamic State will remain until its banner flies over Rome."