Simply put they weren't positioned to do it. They had recently lost many possessions in the 7 years war just a decade before and the costs involved in funding the American war of independence and subsequent costs of rebuilding the french navy severely crippled their finances to a point that the countries debt was one of the reasons the revolution took hold just a few years later as they resorted to unpopular taxation to try and raise the money it required.

Britain could finance its (smaller from the independence war) debts at a lower rate due to the financial institutions it had adopted from the Dutch previously.

Plus it wouldn't make sense, the French were well aware of the difficulties of maintaining a war on the other side of the Atlantic with a hostile nation working to prevent it and they had just made a new potential Ally and trade partner in the formative USA with the help of two other allies, trying to undo this by itself would have been a formidable challenge.

Danial Marston - The American Revolution 1774-1783