"The presence of Al-Qaida, Taliban elements, and indigenous militant sectarian groups poses a potential danger to US citizens throughout Pakistan, especially in the western border regions of the country," the State Department said in a travel warning.
It said threat reporting indicates terrorist groups continue to seek opportunities to attack locations where US citizens and Westerners are known to congregate or visit, such as shopping areas, hotels, clubs and restaurants, places of worship, schools, or outdoor recreation events.
It also noted that the Pakistan Government has heightened security measures, particularly in major cities, some of which have been targets of suicide bombings.
Recently the US top military commander, Admiral Michael Mullen remarked that Pakistan-based Lashkar-e-Taiba (LeT) terror outfit, blamed for the 2008 Mumbai attack, was emerging as a "larger, regional and global threat".
Visits by US government personnel to Peshawar and Karachi are limited, and movements by the government personnel assigned to the consulates general in those cities are severely restricted, it said. Only a limited number of official visitors are placed in hotels for limited stays, the State Department said.