ignore specific directories in htaccess using mod_rewrite

I've got the following code in my .htaccess to strip out index.php from the urls in my CMS-based site.

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php/$1 [L]

This code works great and it routes requests exactly how I want. For example, with URL: http://example.com/contact/ the directory contact doesn't actually exist if you look in the FTP; instead index.php handles the request and shows my contact info. Perfect. Well, almost perfect.

I want to modify this code to specify a couple directories in FTP that should be ignored. For example, if I've got a folder called assets, when I go to http://example.com/assets/ the default DirectoryIndex page is displayed. Instead, I want this directory to be ignored -- I want index.php to handle /assets/.

TL;DR: How can I modify the above code to explicitly ignore certain existing directories (so that index.php handles them inst开发者_开发问答ead of the DirectoryIndex)?

Why not adding this below or before your code?

RewriteRule ^(assets/.*)$ /index.php/$1 [L]