So far, no group has claimed responsibility for the kidnapping.
The U.S. embassy identified the victim as Warren Weinstein, who was working to assist various Pakistani industries. He is believed to be in his 60s.
Officials say as many as 10 assailants broke into Weinstein's home in the eastern city of Lahore early Saturday morning. A motive for the abduction is not known.
His abduction came just 48 hours before he was supposed to come home.
Kidnappings for ransom are common in Pakistan, with foreigners being occasional targets. Criminal gangs are suspected in most abductions, but Islamic militants, are believed to also use the tactic to raise money.
In Washington, the State Department said it was in touch with Weinstein's family and that U.S. officials in Pakistan were working with local authorities on the case. Spokeswoman Joanne Moore would not comment further, citing privacy concerns.
The Associated Press contributed to this report.
