The Italian team are currently third in the constructors' championship, level on points with second-placed Lotus-Renault, and Massa said that they could be challengers.
"I know we have only done two races, but I have a good feeling so far this season," he told Autosport. "The work we did with the F138 over the winter has taken us in the right direction and the car has much more potential.
"Of course, I always want to be fighting for the win, although that did not work out in the first two races, but the signs were good with an excellent race pace and now we have to keep moving forward race by race.
"All I can say is that there are definitely more than two teams that are capable of fighting for the wins and the championship. Our team is one of them, with the car moving forward in the right way and it is delivering results on track that we expected when looking at data in the windtunnel and the factory."
Massa is 18 points behind current leader Sebastian Vettel.