As far as my research in the net has been able to find, hyphenation in Hebrew is used mainly (or even uniquely) in newspaper typeset in narrow columns. There are no hyphenation pattern files for Hebrew that I know of; surely not on CTAN.
The message you get is a long standing misfeature of
babel, which, when it doesn't find hyphenation patterns preloaded for a language, decides arbitrarily to use the patterns for English (
\language0, to be precise).
You can cure the problem with a hack:
% Fool babel
\l@hebrew is the internal command that
babel looks for. You have two advantages with this: the message will not appear and you risk no wrong application of hyphenation. In my opinion, no hyphenation is better than a wrong one based on the rules for (American) English.
If you still get the message, it means that your TeX distribution doesn't define the
nohyphenation pseudolanguage. The remedy then is to say
which works unless your TeX distribution defines hyphenation patterns for 256 languages, and this seems unlikely.