The Saw VI director was hired by Paramount to helm the sequel to Oren Peli's horror hit earlier this month. However, when news of the deal broke Saw backers Lionsgate and Twisted Pictures activated an option in Greutert's contract to force him back to helm the latest 3D instalment.
"I'm in the middle of something really terrible right now," Greutert wrote on his website. "While I fight for justice in this, the important thing is to avoid giving in to hatred and anger, because these emotions are life killers. Hopefully we will all arrive at an amicable solution. Thank you to everyone who is working with me on this."
The filmmaker, who later removed the entries from his site, added in a further post: "I just had the task of telling my 83-year-old mother that no, I'm not going to be allowed to direct the movie we were all so excited about when my family last got together, and that I'm being forced to leave town before getting a chance to see her again.
"Yes, I'll be filming people getting tortured YET AGAIN. So we'll have to put off me making a film she can actually watch for another year. I'm not making this s**t up."
Saw VII 3D and Paranormal Activity 2 are scheduled to go head-to-head at the box office this year, with both opening on October 22.