Johnson has expressed an interest in joining Leeds on a temporary basis and Grayson said: "When you're linked with that sort of player, it shows that you're doing something right as a club.
"We've been linked with some top, top players who any club in the country would take. It shows what we're capable of doing if we need to go out and make signings. But anything we do has to be right for club and the squad."
Leeds have extended defender Tom Lees' loan at Bury until the end of the season.