They said a revised calendar with new dates for France and the recently-postponed Spanish Grand Prix at Jerez would have to wait until the situation became clearer.
The Italian Grand Prix at Mugello on May 31 is next in line but also looks uncertain with the country on Wednesday extending a national lockdown until at least mid-April.
Another race in Spain, at Barcelona's Circuit de Catalunya, follows Italy on June 7 with Germany on June 21 and the Netherlands on June 28.
Whether any will be able to go ahead remains uncertain.
The postponement of the French MotoGP race also raises doubts about the country's Formula One race at the southern Le Castellet circuit scheduled for June 28.
The Formula One season is also yet to start, with two races cancelled and a further six postponed. The sport has said it hopes to run a reduced championship of 15-18 races from the European summer. (Reporting by Alan Baldwin; Editing by Andrew Cawthorne)