United are cruising to the Premier League title but were knocked out of Europe last month by Real Madrid, in controversial circumstances.
Van der Sar thinks that a club of United's stature must perform better on the continent and expects Ferguson to make improvements in that department next season.
He told Sport360: "You want the league of course, that's pivotal but you want to perform in the Champions League, and in the last few years we reached the final three times.
"Last year they went out in the group stage and this year they dropped at the first hurdle against Real Madrid, it's not ideal but that happens sometimes and they are a team in transition and hopefully next season they can go on again."
The former Dutch international stopper is now director of marketing at Ajax, another of his old clubs.