Yes. Air Inter was the only operator of the Mercure. The main issue with the Mercure was that it was engineered to be the perfect French airliner, capable of flying to every major French and European city from Paris.
The problem came from its range though, because as soon as airlines starting thinking of how it would operate from London, Madrid, Rome or Düsseldorf, the planes could really only go as far as France. The Nordics were out of luck too.
When Dassault tried their luck in selling to the US, the same problem came up, but it was even worse. Even flying from New York to Florida was too far for the Mercure.
French government paid for 12 to be built for their operation by the state owned Air Inter (Air France was partially privatised and focussed on profitability over public service). Ultimately, a lot of what was learned from the Mercure was later implemented on the A320, especially the lessons learned when you forget that not all flights fly to or from Paris.