The German marque, and F1's tyre supplier Pirelli, were also "reprimanded" at the end of the so-called test-gate scandal and ordered to pay costs, as the judge's panel found the post-Spanish grand prix test at Barcelona was a breach of the rules.
As a result, Mercedes will not be allowed to field 'young drivers' at the forthcoming three-day test at Silverstone in July.
The carmaker was also ordered to pay a third of the costs of the investigation, with Pirelli to pick up the bill for another third.
"The FIA wishes that lessons are learnt from this case," said the governing body in a separate statement.
"To this end, the FIA will make sure ... that its control of the testings is strengthened."
The statement said Mercedes and Pirelli can appeal.
Decision of the International Tribunal
The Tribunal, after having heard the parties and examined their submissions, decided that:
- Mercedes be reprimanded;
- Mercedes be suspended from participating in the forthcoming “three day young driver training test”;
- Pirelli be reprimanded.
and rejected all other and further conclusions.