Misintent

Misintent is a bad or wrong intention.
The earliest use of this word comes from 1980's, found in Home & Auto.

Person A: I thought I was helping my friend to fight the addiction by giving him some anti-depressants and not giving a proper understanding of how it might lead you to the worst situation possible.
Person B: Well, at that time, you were unable to realize that, it was just a stupid misintent.