"It has come to my attention that a fake Twitter account in my name has been making comments regarding the Stuart Broad catch in the first Test," said Australia great Gilchrist in a statement issued to AFP and other news organisations.
"I am concerned that some overseas media organisations have attributed these quotes to me," added the former Test wicketkeeper, who retired from international duty in 2008.
"Some of these fake Twitter posts may have serious legal consequences," Gilchrist said.
England's Broad had made 37 on Friday when he edged teenage debutant spinner Ashton Agar to Australia captain Michael Clarke at first slip.
Australia appealed for the catch but Pakistani umpire Aleem Dar ruled in the batsman's favour as Broad stood his ground.
As Australia had by that stage used up both their reviews, there was no way for them to overturn Dar's decision even though replays showed a thick edge had deflected off wicketkeeper Brad Haddin's gloves to Clarke.
