Bayern Munich CEO Oliver Kahn said they cannot simply push a button to make striker Robert Lewandowski sign a new contract.
Poland international Lewandowski, who has scored 32 league goals this season and is on course to finish as the Bundesliga's top scorer for a fifth straight year, is contracted to Bayern until 2023.
"We are in communication with Robert and want him to stay with Bayern for as long as possible," Kahn told Sport1. "Apparently, some believe that such talks and contract negotiations are like an online manager's game, where I click somewhere and he then extends his contract.
"Robert is a player who has the potential to score 30, 40 goals every year. Of course, at some point such players get the idea: 'I have achieved everything here and won everything'. Then it takes time to convince them to stay."
Kahn also hit out at the online abuse suffered by coach Julian Nagelsmann, who said he had received hundreds of death threats following their Champions League quarter-final exit.
"You have to be able to take criticism and put it behind you," Kahn said.
"That's part and parcel of playing for FC Bayern. Here, however, boundaries are being crossed. What is going on with people who send death threats to others anonymously? There is nothing more cowardly than discrediting other people and belittling them anonymously."
Bayern are within touching distance of a 10th straight league crown, which they can claim with a win over second-placed Borussia Dortmund on Saturday.