Currently there are no direct flights Marrakech to Croatia
Flights Marrakech to Croatia with 1 stopover:

Flights via Zurich (ZRH), Switzerland
From Marrakech (RAK), Morocco with Swiss  Transfer at Zurich (ZRH), Switzerland Then on to Zagreb (ZAG), Croatia with Swiss
Flights via London Gatwick (LGW), United Kingdom
From Marrakech (RAK), Morocco with British Airways Transfer at  London Gatwick (LGW), United Kingdom Then on to Dubrovnik (DBV), Croatia with British Airways