If the marks have lasted for a long time (more than six months) after the acne went away, then it's not likely that any cream will get rid of them. For red marks, a non-invasive laser treatment may well get the job done, without major expense or risk. If the marks are indented, more invasive laser procedures may need to be considered. I advise a consultation with someone experienced in laser treatments. Such consultations are usually free, or inexpensive. That way you'd know where you stand.
If the marks have only been there less than six months, you're better off waiting them out.
Best.
Dr. Rockoff