Olise was strongly linked with a move away from the German champions during the European transfer window, with Real Madrid and Liverpool among the clubs reportedly interested in the France international.
Bayern, however, insisted that the winger was not for sale and no deal materialised.
Despite that stance, Dreesen admitted that Olise's future could be discussed again next European summer, despite the 23-year-old having a contract with Bayern until 2029.
"Making promises in this business is a tricky matter," Dreesen told German broadcaster Sport1.
"Whether we can keep him permanently is something we will discuss again in the summer."
Dreesen also dismissed reports that Bayern had received an offer for Olise during the recent transfer window.
"That simply wasn't true. That's why I said it publicly. It simply wasn't true. We didn't have any offer on the table," he said.
"We've always said we weren't interested. That's exactly our position."
Dreesen made it clear that Bayern value Olise highly, praising the winger's impact since his arrival.
"Olise is incredibly important for this team. He's a magician on this pitch," he added.
For now, Olise remains a key part of Bayern's plans as they prepare for their next Champions League fixture against FK Bodo/Glimt at the Allianz Arena on Thursday.
Borussia Dortmund defeated Villarreal 3-2 in their UEFA Champions League opening clash at the Signal Iduna Park on Tuesday evening after a Serhou Guirassy double strike.
Liverpool head into their Champions League opener against Atletico Madrid with manager Andoni Iraola facing an early test of his squad management.
Real Madrid secured a 2-1 victory over Inter Milan as Kylian Mbappe climbed the historic Champions League scoring charts at Estadio Bernabeu on Tuesday night.
Harry Kane, Lamine Yamal and Kylian Mbappe headline the 30-player shortlist for the 2026 Ballon d'Or, with the winner to be announced at the ceremony in London on October 26.
