The German manufacturer saw Lewis Hamilton and George Russell finish second and third at Barcelona behind race winner Max Verstappen, moving the squad up to second in the constructors' championship standings.
But a few hours after the race, the team was notified that team members may have breached the regulations in the post-race parc ferme zone that is created in the pitlane.
The FIA requested that a representative of Mercedes, plus the physios of both Hamilton and Russell, should report to the stewards on Sunday evening.
Teams are regularly notified ahead of the race about who and who is not allowed into the parc ferme area following the race.
There is also a strict limit on when physios are allowed to interact with their drivers ahead of the podium ceremony.
In notes sent to the teams by the FIA on Sunday morning ahead of the Spanish GP, it was said: "Other than the team mechanics (with cooling fans if necessary), officials and FIA pre-approved television crews and FIA approved photographers, no one else will be allowed in the designated area once the cars are in the Parc Ferme area (no team PR personnel.)
Source: Autosport