A former senior C.I.A. official says that officials in the Bush White House sought damaging personal information on a prominent American critic of the Iraq war in order to discredit him. Glenn L. Carle, a former Central Intelligence Agency officer who was a top counterterrorism official during the administration of President George W. Bush, said the White House at least twice asked intelligence officials to gather sensitive information on Juan Cole, a University of Michigan professor who writes an influential blog that criticized the war. In an interview, Mr. Carle said his supervisor at the National Intelligence Council told him in 2005 that White House officials wanted to get" Professor Cole. Since a series of Watergate-era abuses involving spying on White House political enemies, the C.I.A. and other spy agencies have been prohibited from collecting intelligence concerning the activities of American citizens inside the United States. "These allegations, if true, raise very troubling questions," said Jeffrey H. Smith, a former C.I.A. general counsel. "The statute makes it very clear: you can't spy on Americans." Mr. Smith added that a 1981 executive order that prohibits the C.I.A. from spying on Americans places tight legal restrictions not only on the agency's ability to collect information on United States citizens, but also on its retention or dissemination of that data.