The 34-year took up the position upon his retirement from football in May, having made over 218 appearances for Villa in all competitions during his seven-year spell at the club.
Petrov, who was diagnosed with the condition in March 2012, has been in remission for the last year, but he feels that he is not quite ready to become involved in the game again just yet.
"Physically, I just need to build myself up some more before I can throw myself into things in the only way I know how, full-on commitment," he told ESPN.
"I intend to spend some time with my family and in six months or so we'll assess how everything is then.
"The entire Villa family have been supportive and I am so grateful for this. I love my new role with the club, I love the involvement and I want to continue to make a valid contribution.
"I have found the day-to-day demands of the job to be a little much too soon. I have spoken to the manager and chief executive and they have been great in helping me to reach a decision while also reassuring me the club will always be here for me."