After reading through the FB Help site, it doesn’t appear that there is a way to do that. If a post is made public, anyone can post a comment. I even looked into attempting to restrict it on both an old post and while creating a new one. In both cases, I couldn’t find an option for this type of control.
@KNOWITALL If I am wrong, can you please provide a link or the step-by-step instructions on how to do so?
When you put a new post on, at the bottom were it say’s post next to there should be a drop down arrow click on that and it should give an option of for e.g. friends, friends of friends and everyone, if you wanted just a select through then you have to go into your friends list and make a group and add the ones you want to say just close friends.
Finally got back to you, sorry. Go to Privacy Settings, then on the left select ‘Timeline and Tagging’, then it goes to ‘Who can post on my Timeline’, etc… Good luck.