Olise has been strongly linked with Real Madrid after an outstanding season and a stellar World Cup with France, while Díaz has more recently been tied to a big-money move to Saudi club Al-Hilal.
Dreesen told Kicker that Bayern had received no contact over either player and were in no mood to sell regardless of the fee on offer.
"I have not heard a single person say: 'You have to sell him for €200million.' He still has three years left on his contract, okay?" Dreesen said of Olise, who joined Bayern Munich from Crystal Palace in 2024 and has since won the Bundesliga in both of his seasons at the club, collecting the club's Player of the Season award in each campaign.
The Frenchman, born in London before declaring for France through the country's youth system, was central to Les Bleus' run to this summer's World Cup semi-finals before their exit to eventual champions Spain.
Bayern are chasing the Champions League this coming season and have no intention of weakening a squad built to compete for it, according to Dreesen.
"We would be stupid, wouldn't we? We have a fantastic team, honestly. Let's get the season under way and score some goals," he said.
Díaz, who signed for Bayern from Liverpool last summer and scored 26 goals with 19 assists in 51 appearances during an outstanding debut campaign, has previously been the subject of a reported €70m opening approach from Al-Hilal, though Bayern's stance on any sale has remained consistent throughout the speculation.
This is not the first Bayern story to touch on Díaz's situation this window; the club has already publicly rejected an initial approach from the Saudi side once this summer, and Dreesen's latest comments reaffirm that no change of position is expected before the transfer window closes.
Both players remain firmly part of the club's plans as they look to build on last season's Bundesliga and DFB-Pokal double.