In the interests of better visibility, teams were told last month they could fix mirrors to the halo head protection device that encircles the cockpit and that became mandatory this season.
The International Automobile Federation (FIA) posted a clarification to teams saying they could legitimately design mirrors to minimise any negative aerodynamic effects but benefits should be minimal. However, there was a feeling among rivals that the winglets Ferrari used in conjunction with the mirrors were being exploited primarily for aerodynamic gain, rather than visibility.
Ferrari's Sebastian Vettel finished fourth and Kimi Raikkonen retired after 25 laps at the Circuit de Barcelona-Catalunya, in a race won by Mercedes' Lewis Hamilton.
The FIA said it "acknowledged that the rules now in force with regard to mirrors are not ideal, and will strive to propose a more complete set of rules in terms of mirror position, mountings, visibility, etc.in the near future, with the aim to get a unanimous support for such changes for 2019".
"As the criteria for determining the eligibility of a mounting are to some extent subjective, the FIA would be available to discuss the legality of a new design before you introduce it in a race, to avoid wasting resource, time or money".
The FIA felt the arrangement broke the rules, and while they allowed the Italian team to keep it on the auto for the remainder of the weekend, they told them to remove it for the upcoming race in Monaco.
"The FIA expect to have full compliance with the present technical directive by the next race", it added.
The FIA added the current rules on mirrors are "not perfect", with a more "complete" set of regulations to be proposed "in the near future" ahead of planned implementation for the 2019 season.