Wolves have already sold Matheus Cunha and Rayan Ait-Nouri this summer and so far signed Fer Lopez in a £19.5million deal.
Pablo Sarabia has departed on a free transfer, while Nelson Semedo has a new four-year contract on the table but is yet to decide on his future and a handful of fringe players could also move on.
Pereira, who is preparing for his first Wolves pre-season, revealed he is concerned about the start to the transfer window and insists he needs more additions this summer to improve the squad.
“We have a good, strong team, but I’m a little worried about the situation," Pereira said in an interview with Spanish outlet Marca.
"We must bring in quality players because expectations are growing.”
He added: "My career has taken many turns, but this is the place and level I've always wanted to be, for years.
"The Premier League is a spectacular league. Every game is a huge, different challenge, and every mistake kills you."
Cunha's departure was expected after he signed a new contract in January that included a £62.5million release clause.
Manchester United triggered the release clause as soon as the transfer window opened, after courting Cunha for some time and Pereira admits the player was keen to leave.
"He's a special player, capable of deciding a match in seconds," Pereira said.
"He has enormous talent. I gave him confidence to put his talent to work for the team, and he's contributed a lot. However, he felt he had to leave, and now he'll have the opportunity to reaffirm his position at a club like Manchester United."
Pereira's arrival in December sparked Wolves' revival, after Gary O'Neil previously fought relegation, and the new boss was able to mastermind an escape from danger.
That was before a brief stumble at the end of the campaign, where Wolves failed to win any of their final four matches.
But Pereira is adamant that Wolves must not fight another relegation battle next season and that they must target a higher finishing position as they look for 'solutions' in the transfer market.
“My expectation is to fight for a mid-table finish," the head coach said.
"I didn’t come to the Premier League to fight to avoid relegation. I came here with the idea of building a strong, consistent project.
"My goal is to create a competitive team that can compete against anyone, and both the club and I are looking for solutions. My ambition, and that of the fans, will be even higher next season.”