Djokovic, who won 24 times by Grand Slam, joined the PTPA in 2020, but he is not among the 12 players alongside the PTPA.
“In general, I felt like I didn’t need to sign the letter because I want other players to move. I was very active in tennis policy,” Djokovic told Miami Open on Thursday.
“This is a classic law, so lawyers are for lawyers, the type of situation. So if there are things with you, there are things that I am with in the lawsuit, and then there are things I don’t agree with.
“And I found that some vocabulary there may have been very strong there, but I think the legal team knows what they are doing and what kind of dialect they will use to have a proper effect.”
Djokovic insisted he did not want to cause cracks in tennis despite his union took action.
“I have never been a fan and support for our sport, but I have always struggled to represent and better influence and the position of players in the world, which I think is not yet where I think it should come and most players think it should be.
“Not only in terms of awards, but also in terms of many points mentioned in the document.
Both ATP and WTA have defended the record and pointed to the awards and security money they offer.
On Wednesday, World No. 3, Carlos Alkaraz announced that it had not supported legal action, and partly because it was not informed of the request.