Option 1
If you have access to http.conf file, open this file and search for htdocs, then replace Options Indexes FollowSymLinks by Options FollowSymLinks. Basically, Indexes is responsible for showing your directory structure.
<Directory "/usr/local/apache/htdocs">
Options FollowSymLinks
AllowOverride None
Require all granted
</Directory>
Option 2
Open your .htaccess file and add the following line. It will give not 403 forbidden warning message
IndexIgnore *
Option 3
Open your .htaccess file and add the following lines. It will give 403 forbidden warning message and that's why you need to add a page for redirection if you want.
Options -Indexes
ErrorDocument 403 https://www.example.com