Lewandowski has been strongly linked with a move to Champions League winners Real Madrid, with some reports suggesting a deal has already been agreed.
But Reschke says Bayern have no intention of letting Lewandowski leave.
"He will play in the upcoming season for Bayern, there is no doubt about that," he is quoted as telling Radio Crc.
"He has another three years on his contract and we know that we have the best striker in the world in our squad.
"That's why there is no possibility he will be sold."
Should Lewandowski depart, it is thought Napoli's Gonzalo Higuain would be top of Bayern's shopping list.
Reschke said: "Gonzalo Higuain is among the three or four best strikers in the world, but at the moment we have the best in Lewandowski.
"It is therefore pointless to sign another forward, for us and the players."
Lewandowski scored 42 goals in 51 appearances in all competitions last season.