拒绝访问子文件夹但不访问文件

here's what I aim to do. I have in my public folder numerous folders like images, css, javascript and I want to deny access to these folders but not files within them. Which seemed easy but then there're all those sub folders in the images folder like icons, photos and users which has a sub folder for each user and this task became a little pain in the neck. Since I failed to deliver in a single htaccess file my only option left was to create an index.php in every sub folder and hope for the best. That's why I'm asking if someone can provide a recursive way to limit access to all sub folders but not files within them with a single htaccess file? I'm using apache.