The Maranello squad has generally been the stronger team in the first five races of the 2024 season, being the only non-Red Bull winner in the Australian GP thanks to Carlos Sainz's victory.
But McLaren's Lando Norris had the upper hand in the last race in China, where he was Max Verstappen's closest challenger to finish in second.
Ferrari duo Charles Leclerc and Sainz endured one of their weakest weekends of the year and finished a distant fourth and fifth in the race.
Asked if Ferrari had taken a step back compared to McLaren in China, Vasseur said that the gap between the two teams will hinge on maximising car performance at each individual track, as he reckons there is little to choose between the two.
"I think it's a matter of a tenth or half a tenth," Vasseur said. "In Melbourne for example, after 60 laps we finished the race eight seconds in front. It's more a matter of extracting the best of what we have.
"And honestly, we are speaking about development. First, as a team, we have to get the best of what we have, and we didn't do the job this weekend on this. It's not that the situation is changing massively from one weekend to the other one.
"It can be a bit track-related, tarmac-related. I think it was very difficult to understand the tarmac [in China], also due to the format because we did a stint with soft on Friday morning and then we went to the race with medium and we didn't do the medium before, we did one lap in qualifying.
"It means that this kind of understanding of the situation, let's say or approach of the situation can make a difference at the end because we are speaking about one tenth, we are not speaking half a second," he added.
Vasseur says the tight group of cars chasing Verstappen means there has not been a "normal" weekend that allows him to have a clearer picture of which team is ahead.
The Frenchman insisted the smallest of details will make a difference, as he reckons China exemplified.
"There is no normal weekend. It's the beginning of the season, so we have the window that the whole is very, very tight," he said.
"Perhaps Max sometimes is a bit faster. But we have a pack with six or seven cars in one tenth. That means that for details you can move from hero to zero.
"And when you start from P9 the race is much more difficult because you have dirty air on the first laps, even if you are faster, but basically even if you are faster you struggle to overtake because if you don't have the big gap, you damage the tyre for the first 10 laps and then you are dead.
"I think it's really a matter of putting everything together. We didn't have a clean weekend on our side, but we made collectively too many mistakes.
"And we know that in this group, if you don't do the perfect job you won't be in front."
