Apparently the Tunisian government provides an exception to the 14 day quarantine (or 7 day quarantine if you pay for and pass a COVID test after the first 7 days in quarantine) if you are booked on an organized tour, or have made private arrangements with a guiding firm to take you on a tour.
Otherwise, there's no escape from the quarantine requirement.
For what it's worth, Tunisia did a really good job controlling COVID infections during the first half of the year (only 1,100 infections up to the end of July), but things have gone all to hell in the past month - the infection rate is soaring, with 996 cases reported on one day alone (Sept 21) - that's almost as much as the cumulative total March to July! Worse still, there have been over 5,600 new cases reported in the past two weeks (Sept 8 - 22).
For information about what countries are on the "red list" published by Tunisa (meaning, they won't let you in at all, even with a quarantine period), see this article published 2 days ago:
Tunisia Red List Update. It's in French, but you'll be able to figure out the country names easy enough. Be careful how you interpret that list - unless you fly into Tunisia from Poland (unlikely), you'll probably be going through France, which is now a "red zone" (no entry from) country, or Italy, whose status could change at any minute. In other words, the Tunisians might consider the country of your port of departure, rather than what passport you hold, when applying entry restrictions.
My motorcycle is presently in Tunis - I left it there in early April when I flew out on a repatriation flight. I very much want to get back to Tunisia to pick it up and resume my riding (either in Tunisia or elsewhere), but I don't think now is the time to go - sadly, COVID is out of control in Tunisia now.
Michael