I have an app that posts a message to a person\'s Facebook Timeline / wall. Is there a way to disable commenting or likes on that post via the Graph API?
No that's not possible with graph api!
You can only disable commenting for a post if the end user is a 'page' or public profile, but not if posting to a normal user.
No - whether or not a post can be liked or commented on is determined by the privacy settings of the user who posted the content - for example, you may not be able to comment on posts in a Group, even if the posts are visible to you, because the Group admin has selected to only allow members to interact with content there. Similar restrictions are in place for user profiles (allowing comments on content posted to a user's timeline) and pages (e.g. only fans of the page can comment).
There is no way to make a post and have an option or parameter on that specific post which prevents Likes, comments, sharing, etc for that content.