RewriteEngine on
RewriteCond %{HTTP_REFERER} ^http(s)?://([-a-z0-9]+\.)?site1.com.*$ [NC,OR]
RewriteCond %{HTTP_REFERER} ^http(s)?://([-a-z0-9]+\.)?site2.com.*$ [NC,OR]
RewriteCond %{HTTP_REFERER} ^http(s)?://([-a-z0-9]+\.)?site3.com.*$ [NC]
RewriteRule .* http://herhangibirurl.com/yasak.jpg [R,L]