Diego Costa has been ruled out of Chelsea's Champions League group game against Maribor on Tuesday with an ongoing hamstring injury.
The Spain international missed his first Premier League match on Saturday as the Blues triumphed 2-1 at Crystal Palace to maintain their five-point lead at the top of the table.
Costa featured twice for Vicente del Bosque's team during the international break and although he scored against Luxembourg, doubts surfaced over his fitness.
Mourinho said: "It's the same problem that he [Diego Costa] is having. Now an injury, not almost an injury. He's not training because he's not in condition to do it.
"Tomorrow he can't play. Let's see what happens next weekend [against Manchester United] but what matters is tomorrow and tomorrow he can't play."
The Blues are also without John Obi Mikel, Ramires and Andre Schurrle for their Group G game and, when pressed further on Spain's treatment of Costa, Mourinho revealed his frustration with the selfishness of some national team coaches.
"There are no rules, no laws to protect [the clubs]," he added. "It's just down to the mentality of the national team coaches. It is up to them to take good care of the players or to work in a selfish way.
"I'm not the guy to tell the players not to go, I don't tell them to pretend they have problems. I stimulate them to go, I like them to go. We like our players to play in the big competitions so we're always positive about our players going.
"After that you have national coaches and medical coaches who want to establish a relationship and they want to know and some others simply don't care. This is something we can't resolve. It's something that is out of our hands.
"I had in my career a few of them in permanent contact with me. I had managers with very open communication, and I had others who year after year I don't have one single text or call from them.
"If one day I become national coach - I hope in 20 years time - I will do it my way, and with so many years this side of the situation, I will have good conditions to be good for the clubs and take good care of the players and the clubs.
"It hurts. You are not happy when you give players in good conditions and you receive them in bad conditions."
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