I have Egyptian passport and American visa in my passport. Can I enter Croatia with my American visa or do I have to apply for Schengen visa to enter this country?
Having a US visa does not include entry into Croatia. The Republic of Croatia Ministry of Foreign and European Affairs says:
[O]nly those who are holders of valid Schengen documents, as well as national visas and residence permits of Bulgaria, Cyprus, and Romania do not require an additional (Croatian) visa for Croatia.
Your visa application would be made through the Croatian Embassy in Cairo
3 Abou El Feda Street, Zamalek
Tel (+20) 22 73 55 815
(+20) 22 73 83 155
Fax (+20) 22 73 55 812