Lewis Hamilton led Valtteri Bottas in a Mercedes one-two in first practice at the French Grand Prix.
Hamilton was just 0.069 seconds ahead of the Finn, with Ferrari's Charles Leclerc third, 0.373secs off the pace.
The team will go before the stewards at 13:15 BST to make their case for the penalty to be reviewed on the basis of new evidence.
If the stewards accept that there is justification, the offence - of rejoining unsafely and forcing Hamilton off track - will be looked at again.
Vettel was fifth in practice, behind Red Bull's Max Verstappen, who was 0.880secs behind Hamilton.
Ferrari spent the session trialling upgrades to their car, including a new front wing, that they hope might start moving them towards Mercedes' pace.
A number of drivers complained about the tyres wearing out quickly, and there were spins and off-track moments as the limits of grip were explored.
Red Bull's Pierre Gasly was sixth, ahead of the McLarens of Lando Norris and Carlos Sainz and Renault's Daniel Ricciardo.
Ricciardo is using an upgraded engine this weekend, along with a number of aerodynamic upgrades that are on both Renaults, which they team hope will move them clear of the rest in the battle for fourth place.
Team-mate Nico Hulkenberg has the new car parts but not the new engine because taking it would have meant a grid penalty and Renault wanted to avoid that at their home race.
There are also new, upgraded Honda engines in the cars of Verstappen, Gasly and Toro Rosso's Daniil Kvyat, who will start from the back of the grid as a result for using too many engine parts this season,
The Russian's team-mate, the Anglo-Thai rookie Alexander Albon, will get the engine at a later race to avoid both cars getting penalties at the same event.