Luis Enrique will make sweeping changes to the Barcelona roster ahead of the 14-15 season.
Enrique was named new manager to replace Tata Martino this week.
"The players must know that you cannot let a year pass at Barça," he said. "If they are not at the level required then there will be changes. We will reinforce the team in the best way possible, to be as competitive as possible. There is a market there -- teams ask a lot of money for players. You must manage it all. We will reinforce, maybe in all lines of the team, to have the best players for the club and for me."
There has been speculation that a host of high-profile players including Xavi Hernandez, Cesc Fabregas and Javier Mascherano could make way.
Asked about the trio, he said: "I know Xavi. He is a friend, an ex-teammate. I could tell you great things about him. We will sit down and talk, and see what he wants and what we want. He has a big date with the World Cup.
"I do not want to talk too much about individuals. Good and important players will stay. We will look at everyone and then see what we do. We do not have to make decisions now. We have time."
Barça didn't win La Liga or Copa del Rey and were eliminated from the Champions League in the quarterfinals.
"Barça has an attractive idea of football, but we also have to defend and concentrate, and work hard. The way of playing will be the same as for many years now, but you must evolve the ideas, and improve on them, based on players you have."