F1 authorities are looking to add a new team or two to the grid for 2021.
Recently, FIA president Jean Todt said he would "love" to see a full grid of 12 teams, and Liberty Media is actively devising a new Concorde Agreement that would allow it.
Renault is opposed to the trend.
"It's already a challenge for a team like us to compete against the top three teams who have 30 to 40 per cent more resources than us," said boss Cyril Abiteboul.
"But if they are now capable of combining their resources with other teams, or getting the benefit of synergies within the scope of a budget cap, that's a problem for us."
He also said it's a problem for at least "two other teams" in particular, obviously referring to struggling independent outfits McLaren and Williams.
"It's a serious topic because maybe we are now saying 'We have three top teams and that will be it'. And anyone joining will have to accept they will not be in a position to be competitive," said Abiteboul.
With their 'B' teams shaping and adding up, Ferrari (Alfa Romeo and Haas), Mercedes (Racing Point) and Red Bull-Honda (Toro Rosso) therefore don't see the need for new teams in F1.
"I think we are in a decent place right now for formula one," said Mercedes' Toto Wolff in Melbourne.
Red Bull's Christian Horner agrees: "I always go quality over quantity.
"I think we've got ten teams that are in pretty decent health at the moment. I think none of those teams that came in a few years ago are still here today.
"I think we've got a good balance at the moment. I would prefer that we look after what we've got and have good quality and a closer grid than just inviting more entries for the sake of filling the grid and there being more cars to lap," Horner added.