Michael has told an attorney, his daughter is in the danger zone ... a substance abuser, he says, who is hanging with the wrong group of people, including Dina Lohan.

Michael will meet with lawyers early this week, and there's one thing he does want -- he will NOT become Lindsay's conservator, because he doesn't want to run her finances so people will pass it off as a money grab. We're told Michael wants the judge to decide who to appoint conservator, but he says it CAN'T be Dina.

Michael told the lawyer the first thing he will do if there's a conservatorship is convince the conservator to send Lindsay to rehab, without the influence of the other people in her life. Michael says every time Lindsay has been to rehab -- including at Cirque Lodge and Betty Ford -- "She went in dirty and didn't come out clean," and he blames it on the people in her lives who helped fuel her addiction.

Michael also told the lawyer he wants the conservator to somehow convince Dina that they need family therapy. He says Dina has always refused it in the past, and it has been a big stumbling block in Lindsay's recovery.