How can I send money to my Russian MasterCard from Tunisia?

Fehmi, as a Russian living in Tunisia, I know very well about the laws of both Tunisia and Russia.

The location of your bank account is irrelevant, what is relevant is the currency in which that account is denominated. That is to say, if you have a USD bank account in Russia, then you need someone outside of Tunisia to whom you can give TND in Tunisia, and after he or she takes a comission for him or herself, they can wire money (in Euro, USD or RUB) to your Russian bank account.

You've already "commited a crime" (although no-one cares) by opening a bank account (only if you were resident in Tunisia when you opened an account for youself in Russia: if you were living there, no crime has been commited). You can use that debit card (as does just about every foreigner that I know) in Tunisia, and after the Russian bank and Tunisian ATM have taken their comission(s), you will get the amount you requested, given to you in TND.

If you opened the account while legally resident outside of Tunisia (you can be a resident of Algeria or Morocco and have a bank account in Russia, addressed to your DZ/MA address - what is important is that you do not use your Tunisian address on the bank account), you can wire the money to your TND bank account and the bank will convert the money into TND. There are large international wiring fees, so it would be cheaper for you to withdraw this money in cash from an ATM in Tunisia. It will save your money sitting in the BCdT for months while the paperwork explaining where this money came from is processed.