Borussia Dortmund were eliminated from the DFB-Pokal at the quarter-final stage by the Bavarians on Wednesday, but the nature of their exit riled the 47-year-old who slammed the Bundesliga leaders for imitating his side's style of play.
In his weekly column for Bild, Netzer wrote: "I expressed my admiration for Jurgen Klopp and his work at Dortmund several times in the past, but his latest words [to the press] showed a lack of composure and sovereignty.
"I think you could detect a hint of contempt from Klopp's words for his coaching colleagues, and the Bayern hierarchy have noticed it.
"He has let his inner self speak [to the media], and this shows that the 1-0 loss in Munich is hurting him a lot.
"This is more than a defeat for Klopp. That's why he let himself make this verbal blunder."
Netzer, a team-mate of Heynckes at Borussia Monchengladbach in the 1970s, put the 1-0 midweek defeat down to a lack of squad depth - namely the failure to adequately fill the void left by Mats Hummels in defence.
"Mats Hummels was missing in this game, but not only for his defensive performance because he is more than just a defender," he added.
"Hummels is a stalwart in defence, and now you have seen that without him functioning as the side's anchor, it becomes very difficult [for Dortmund].
"Dortmund's first XI is brilliantly cast, but that is where the problem lies. Bayern don't have those issues anymore. They have eliminated them.
"The increased competition for places means [Bayern's] level has improved considerably. This could also give them a decisive edge in the Champions League."