AFAIK squid can't do this on it's own... the best you can do with squid on it's own or a redirector is filter based on words in the URL, which kinda sucks... you should probably go for a "true" content filter like DansGuardian, but i don't think they have built-in support for Arabic, so you'd need to write your own Arabic language files for it...
http://www.dansguardian.org/