Costa has been absent from Chelsea's last four matches because of injury, but despite being in line to return against Queens Park Rangers on Saturday afternoon, Mourinho has revealed that his time with his national team has left him needing "special care".
The 51-year-old told reporters: "He played for the national team and we lost him for four matches. Crystal Palace, Maribor, Shrewsbury and Manchester United, four matches in three different competitions. Now he is again available but he needs to be under special care.
"I'm always supportive of players playing for their national teams when they are in the condition to do so. But I'm nobody to stand in the way of the national team, I can't stop him going away with his country."
Costa has scored nine goals in as many games since his move from Atletico Madrid in the summer.