You need to use the decoded pattern, not the encoded one. The URI's get decoded before mod_alias/mod_rewrite get applied.
Redirect 301 /קורסים-וסדנאות.htm http://samedomain.co.il/%D7%A4%D7%A8%D7%96%D7%A0%D7%98%D7%A6%D7%99%D7%94-%D7%91%D7%90%D7%A0%D7%92%D7%9C%D7%99%D7%AA/