The Spaniard finished second in the season-opening Australian Grand Prix in Melbourne while new Ferrari driver Kimi Raikkonen eased to victory on the Albert Park Circuit.
Both Alonso and team-mate Lewis Hamilton, who enjoyed a stunning debut in F1 after making the step-up from GP2, were unable to catch the Finn, who at one stage stretched his lead to more than 17 seconds.
And the 25-year-old former Renault driver believes McLaren’s MP4-22 car will need to be made faster to win races this year.
“We are here to win the world championship and we know that the race is the most important part of the weekend,” said Alonso.
“In qualifying we seem to be quite competitive with no big problems, and then in the race I think we are not as quick as the Ferrari in the long runs.
“So it is the area in which we are trying to improve and where everyone is trying to improve compared to Ferrari. As I said, (in) qualifying I think two or three teams can fight with Ferrari, but in the race, no-one.”
Alonso, as with the rest of the drivers, used the two specifications of the Bridgestone tyres for the first time. Under 2007 regulations, each team are supplied with the same two compounds as their rivals at each race.
He was unable to determine if they will make much difference: “It was difficult to say because in the last part of the race no-one was pushing because the positions were quite fixed, so we didn’t push the last set of tyres hard to see how they were.
“I think both of them were quite similar at the end with the track conditions we had.”
Team principal Ron Dennis praised both Alonso and Hamilton as their finishes ensured McLaren went to the top of the embryonic Constructors’ Championship. He targeted next month’s Malaysia Grand Prix as a further chance to develop the cars.