After finishing a distant sixth and almost being lapped by Lewis Hamilton in Sunday's Spanish Grand Prix, he said Ferrari had struggled from the start as they completed a year without a win.
Hamilton finished just 0.6 seconds ahead of his Mercedes team-mate Nico Rosberg to move on to 100 points for the season and into the lead of the title race ahead of Rosberg, on 97.
Alonso is sitting third with 49 points, four points ahead of defending four-time world champion Sebastian Vettel of Germany.
Alonso's and Ferrari's last victory came in the 2013 Spanish Grand Prix and on Sunday he was only three seconds away from being lapped by Hamilton in front of his compatriots.
The two-time world champion, in 2005 and 2006, said: "It was tough, but nothing surprised us.
"We had very low grip throughout the race. We struggled with the start and did not make any places on the first corner and we were stuck in traffic for 90 percent of the race.
"We are in a similar position (as before Barcelona) unfortunately. The gap this year is amazing from the Mercedes -- 40 seconds, so fair play ...
"And we need to raise our game because Mercedes are showing the potential of these cars."
Fernando Alonso Admits That Ferrari Face Tough Task Ahead
Advertisement