Sebastian Vettel has said that Ferrari's aggressive strategy of full attack will not always work out for the ambitious Maranello team.

The German insists that he is driving a better car than in 2015, even though a year ago he had already won the first of his three races for the season.

"We have become better, it's just the results don't show it yet," Vettel told Germany's Sport Bild.

"There is still a gap to Mercedes, that's true, but it has become much smaller. You can't just move mountains overnight."

Barcelona was a setback for Ferrari, with the red team not even able to capitalise on Mercedes's double-DNF, as Red Bull's Max Verstappen won.

Ferrari have been working on the cause of their sudden qualifying pace problem at the Barcelona test this week.

"We are giving everything - sometimes maybe even a little too much," said Vettel. "But we have to try everything."

Asked, then, if errors are forgivable as Ferrari pushes to catch and beat Mercedes, Vettel admitted: "No. The technical problems we have had were not in the plan.

"But catching up is always a balancing act. Perhaps some improvements have come a bit too early, but if we think something is an advantage in speed, we want to bring it to the track as quickly as possible."

The season continues next weekend with the Monaco Grand Prix.