ethnic-related questions by immigration officer

I have faced a disturbing situation when entering the territory of Morocco as a tourist. I am a French citizen, with obvious Middle-Eastern face features and name, and carrying a French passport.

The immigration border officer first thought I was a Morrocan citizen who was hiding a Moroccan citizenship (it seems to happen a lot) and asked for my Moroccan ID card, which i didn't have since i am not one of their citizens.

Then he asked for my "country of origin", stating that at least one my parents originated from the Middle East(which is true). He then wanted to know the nationality of my parents. I then answered the questions since I didn't want to have trouble with the local authorities. He then wrote the answers on his notebook. The same situation occured when leaving the country and happened with a number of other French citizens who I know.

I consider such questions very intrusive and not part of the officer's business.

How should one behave in this situation ? Is there an international convention on which I can rely in order to avoid such ethnic profiling ?