UEFA's 54 member nations voted to bring in the tournament, which will act as a replacement for the majority of international friendly fixtures, from 2018.
The league will be made up of various groups and pools with teams fighting it out for extra spots at UEFA's European Championships, while also battling for promotion and against relegation.
While FIFPro commended UEFA for their attempts to replace friendlies with competitive games, the body also outlined a number of potential issues players participating in the Nations League may face.
For instance, two such problems put forward by the organisation were the increased strain faced by players playing in more competitive games and the possible restrictions it will cause for youngsters looking to gain international experience.
"It should be clear that there is a difference in a friendly match and a competitive match," said Tijs Tummers, FIFPro director of player services, in a statement.
"As we understand, the Nations League will be another prestigious competition. As a consequence, that implies an increase in the workload for the group of top players."
In terms of scrapping friendlies, Tummers expressed doubt over whether doing so represents a pressing priority at the top of the game.
"Mostly, the countries organise a friendly against an opponent of equal quality," he added.
"What should be thought over is the amount of qualifying matches between teams that have an enormous gap in talent level.
"Very often you see a match between nations that are more than 100 places separated from each other on the FIFA rankings. Even with the new Nations League, those matches will remain on the international match calendar."
