You probably won’t find a site like that for free…Creating that kind of data base and search engine is an expensive endeavor. There is a program called Horticopia that enables you to search based on form, color, seasonal bloom, soil, water, etc, etc. It’s a great program for finding plants appropriate for your region but even Horticopia doesn’t have every plant and misses a lot of the basics. One of the factors you need to consider in your search is; will you be able to source the plants in Morocco? There’s no point in identifying “native” plants if you can’t get them on the scale you’ll need from local nurseries.
Also, is there a reason you are going with “natives” vs. “adapted” species? There are a lot of great plants from around the world that will work in that region…