The US embassy in the Saudi capital Riyadh has cancelled all consular services for Sunday and Monday due to "heightened security concerns".
In a statement, the embassy said consular services in Riyadh, Jeddah and Dhahran would not be available.
It urged US citizens to take extra precautions when travelling in Saudi Arabia and to keep a low profile.
On Friday, the embassy warned that Western oil workers could be the target of militant attacks.
It said it had information that "individuals associated with a terrorist organization" could be targeting people working in the oil-rich Eastern Province.