In a statement, issued by the US embassy in the Gulf kingdom's capital, Manama, the alert "encourages all American citizens to avoid places where Westerners are known to congregate and to reduce unnecessary travel".
"The embassy is seeking more information on this threat", an embassy spokesperson told Aljazeera.net.
The alert covered the holiday season, through to 2 January 2004.
The embassy also reminded resident Americans to "remain aware of their surroundings, be vigilant about their personal security, maintain an unpredictable daily schedule and vary the routes used to travel to and from their places of work and residence."
On Sunday, the US government raised its nationwide security level from yellow, denoting an "elevated" risk of attack, to orange or "high" risk, amid concerns of an impending domestic terrorist attack.
In a statement issued of "worldwide caution", the US State Department said it "remains deeply concerned about the security of US citizens overseas. US citizens are cautioned to maintain a high level of vigilance, to remain alert and to take appropriate steps to increase their security awareness."
"We are seeing increasing indications that al-Qaida is preparing to strike US interests abroad", the statement added.
"We are seeing increasing indications that al-Qaida is preparing to strike US interests abroad"
US State Department
The state department said it had stepped up security at overseas embassies and missions after raising the security alert.
In November, the British embassy in Bahrain warned its nationals of a high risk of terrorism against Western targets, though the US embassy there said at the time, it had no specific information about an imminent threat to US interests in the Gulf kingdom.
The warning was issued after suspected al-Qaida bombers blew up a housing compound in Riyadh, Saudi Arabia.