Despite Ferrari starting the season off the pace, Alonso managed to pull out a 40-point lead over Webber, then his nearest rival, by the summer break.
But when Red Bull rediscovered its dominant form in the final run-in, Vettel was able to edge ahead and eventually clinch the title by three points.
Asked if he felt pity for Alonso, Webber replied: "I don't think he put a wheel wrong all year. That's the reason I think he's so disappointed. He felt he probably did everything he could.
"Was it his best season ever in terms of what he did? It could well be. He couldn't have done much more."
Webber noted that his defeat of Alonso in the British Grand Prix had proved crucial given Vettel's slender eventual winning margin.
"To still miss out by just three points - it was lucky I passed him at Silverstone..." said Webber.
Vettel said he would prefer not to pass judgement on his adversary's performance.
"I respect him as a driver for the fact he is fighting and he is one of the best drivers we have in F1, but you look after yourself," said the champion.
"We were fighting quite a lot as well. I don't want to put a perspective on who was fighting more or harder, that's not the point.
"It's a long season, there's a lot of races and in the end the guy who wins the most points wins the championship.
"Of course I am very happy it was us and not him."