He said details of the intelligence report were delivered to the Fifth Region Police Commander Suthep Dejraksa last week so that he will closely monitor the situation.
An untoward incident would have a negative impact on national security, he said, adding that the alert will continue until the joint Thai-US military exercise, code-named Cobra Gold 13, is finished.
Cobra Gold 13, which involves troops from the US, Thailand and allied countries on exercises in Thailand, began yesterday and continues through Feb 21.
Mr Chalerm gave assurances that the reinforcements at the US consulate will not jeopardise a trip by Prime Minister Yingluck Shinawatra to the northern region later this week.
It was reported that the security unit at the American consulate has contacted provincial authorities seeking round-the-clock protection.
Deputy Premier Chalerm later revealed that al-Qaeda has targetted US military personnel attending the joint exercise.
He said he has learned that some of the group members left the country and only a few remain in Thailand, under the close watch of the Thai authorities. An arrest could not be made since they did not commit any crime, he explained.
Prime Minister Yingluck Shinawatra has been notified about the matter and she has instructed agencies concerned to tighten security, according to Mr Chalerm.