A cardinal rule of the Obama administration was that no White House official ever interfered with any independent investigation led by the Department of Justice. As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any U.S. citizen. Any suggestion otherwise is simply false.That leaves open the possibility that the Department of Justice obtained a warrant in a criminal probe of some sort. If that is the case then Trump is probably in deep shit. When someone is subjected to surveillance by law enforcement he or she is notified after the fact. The White House has not responded to the Associated Press regarding the source of Trump's assertion.
A story on Breitbart and other right wing outlets claimed that U.S. officials had obtained a warrant under the Foreign Intelligence Surveillance Act to review contacts between computers at a Russian bank and Trump's New York headquarters. If that is the case then Trump is probably in really deep shit. Trump has a history of tweeting about unverified stuff that he reads or hears. He is inherently irresponsible.