You could try this:
<IfModule mod_rewrite.c>
RewriteEngine On
# Lexographic string match
RewriteCond %{API_VERSION} <=20051115:5
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ index.php?url=$1 [QSA,L]
# Lexographic string match
RewriteCond %{API_VERSION} >20051115:5
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ index.php?url=$1 [QSA,L,B]
</IfModule>
Or install mod_version and try:
<IfVersion <= 2.2.6>
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ index.php?url=$1 [QSA,L]
</IfModule>
</IfVersion>
<IfVersion > 2.2.6 >
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ index.php?url=$1 [QSA,L,B]
</IfModule>
</IfVersion>