Ferrari has slipped back in the last two events, with the two cars finishing ninth and 10th at Silverstone, and seventh and eighth in Hungary last weekend.
However, Vasseur says the Italian outfit should just focus on its own performance and not get too hung up about the pacesetters.
"Red Bull are in front but I think the feeling was quite the same when Mercedes was in front a few years ago,” he said. "The most important thing is to be focused on ourselves, to try to get the best from what we have, to minimise the mistakes, do a better job and then comes what will come.
"To catch up, it's not that you are thinking about the Red Bull and thinking what do we have to do? We have to work on ourselves. We are developing, we are developing on every single direction, we are trying to improve aero, suspension and whatever we can do, and we are pushing like hell to do a better job.
“But if you have a look also, and I think this is crucial, with the bouncing and so on it's not when you are bringing an upgrade that you are making a huge step forward.
“We brought big things in Barcelona, and we were potentially better the week after. I think Alfa Romeo brought something last week or two weeks ago, and they did a very good job this weekend [in Hungary], at least in quali.
“It means that the understanding of the upgrade is also crucial. And it's not just about making a headine package."
Vasseur noted that it’s hard to make progress in-season in the light of the cost cap restrictions.
"I think that everybody is improving,” he said. “But the reality also of the regulation and the cost cap is that we are improving much less than in the past. It means that when there is a real gap, it's quite difficult to catch up.
“From one weekend to the other, if you look over the last four or five weekends, it was one time us ahead in quali, one time McLaren, one time Mercedes. But we are always behind Red Bull and at least in the race, there is still a huge gap."
He stressed that the margin to the top team in qualifying has been consistent over the year thus far in qualifying and race trim: "I would say that it's like this from the beginning of the season, because if you have a look I think over the quali we are average something like 0.2-3%, and probably 0.7% more in the race, and I think it's true for everybody, it true for Mercedes.
“In general it's more Red Bull with more performance in the race than the others who are slower. And it's not today, it was probably a bit less true in Spielberg, but overall it was the case all season."
