Spurs face Chelsea in the competition on Tuesday (29.09.20) which forms part of four games in seven days and Mourinho admits that he may not be able to field a strong team due to Spurs' Europa League match against Maccabi Hafia on Thursday (01.10.20) and Premier League game against Manchester United on Sunday (04.10.20).
He said: "I would like to fight for the Carabao but I don't think I can.
"The group phase of the Europa League gives us a certain amount of money that for a club like us is very important."
The 57-year-old manager believes that the scheduling of the tie gives his former club an advantage.
Mourinho said: "I think you can imagine that with a game on Thursday that decides a very important thing for us, I think the EFL made a decision for us.
"They didn't even create a problem - they made a decision for us. So that's the decision.
"Chelsea played Saturday, they have Sunday and Monday [off] then they play Tuesday and then they play again on the weekend.
"So their fantastic squad, if the manager decides not to rotate, he can perfectly play with the players that he wants."