Koeman, 57, was presented at Camp Nou on Wednesday after signing a two-year deal to replace the outgoing Quique Setien. He takes over a Barca side rocked by their biggest ever European defeat, which confirmed a first trophy-less season since 2007-08.
President Josep Maria Bartomeu said that it's time to say "farewell to some club legends" as part of a major overhaul of the squad. He named several players who are not for sale, including Lionel Messi, but the names of anyone else over the age of 30 were conspicuous by their absence.
"I think there have to be changes," Koeman said in a news conference. "But, in my opinion, it won't be a revolution. We will take decisions based on what is best for the team."
Koeman refused to speak about individual players, with the exception of Messi, but did say age isn't necessarily a factor when it comes to deciding who stays and who goes.
"I don't think a player aged 31 or 32 is finished," he added. "It's all to do with the hunger they have to be here and to give their all for the club.
"There are players at 20 that lack that. I only want to work with players that want to be here. If they don't want to be here, they can tell the club. I want to work with people who want to give their all for Barcelona, no one else."
Messi's future is a hot topic at the moment. The forward has maintained his silence following the defeat to Bayern amid reports he wants to leave the club. Koeman says he has a chat pending with the Argentine, who has a contract until 2021.
"I don't know if I have to convince Messi to stay or not," the coach said. "Of course he's the best player in the world and you want the best player in the world in your team, not playing for the opposition.
"I would love to work with Messi because he wins games. If he has his usual performances, I will be delighted if he wants to stay. But he also has one year on his contract, so he is a Barcelona player. From there, we have to talk to him. I hope he continues here for more years."
Koeman, who left his role as Netherlands boss to replace Setien, has a long history with Barcelona. As a player, he was part of Johan Cruyff's "Dream Team" and scored the winning goal when the club won the European Cup for the first time in 1992.
However, he has always maintained that it's his dream to manage Barca and he's delighted to finally land the job -- even if he acknowledges the scale of the task facing him.
"This is a happy, proud day," he said. "Everyone knows what Barca means to me, it's my home, so to have a chance to train such a great team is a challenge.
"It's not an easy one. Even during the good moments, it's not easy to be at Barcelona because the club demands the very best. But I like that, it's how it has to be.
"The image of the other day [against Bayern] is not the image we want. We are going to work to recover the prestige of a club that is still the greatest in the world."