The pair have been quoted to be seeking pastures new following the arrival of Andriy Shevchenko this summer.
Argentinian Crespo has been quoted as saying that he has turned down Roman Abramovich's millions in order to return to Italy.
Ivory Coast hitman Drogba has also hinted at leaving despite suggestions he could partner Shevchenko.
But Mourinho said: "Both Hernan and Didier are Chelsea players.
"If they desire to leave Chelsea so much then I will have to let them go if the conditions are good for Chelsea.
"Everybody knows what Hernan and Didier have done in the last few years.
"We also have some good young strikers here but all believe we have a better squad now with the strikers we have.
"The squad is full of quality and it gives me the ability to try different combinations for different games.
"All the players here will play a big part in our success and we need the team to win the league."
Damian Duff has already left the club for Newcastle after seeing very little action with the Premiership champions.
And the departure of Asier del Horno to Valencia has left Wayne Bridge as the only senior left-back in America.
Chelsea are being strongly linked with a move for Arsenal and England man Ashley Cole but Mourinho claims a smaller squad is better.
He said: "I don't have five important players here at the moment but when they arrive the squad will be strong.
"It will be a smaller squad than in the past - of 20 players - but there will be space for everybody here.
"We won't have a problem with players being first choice, second choice and third choice and players being unhappy.
"At the end of the day everyone will help us during the season and we have such great quality and all the players are fantastic which gives us a better squad than before."
it will be interesting if both crespo and drogba do go but i think they will personally stay..