Spain have been involved in a club-versus-country row with Chelsea over the past two months regarding the availability of striker Costa, who has been contending with a persistent hamstring injury
Another potential clash was avoided when Spain coach Del Bosque opted against selecting the 26-year-old for the upcoming Euro 2016 qualifier with Belarus and friendly against world champions Germany, citing that it was the best decision for his fitness.
Costa subsequently played and scored in Chelsea's 2-1 win over Liverpool on Saturday, leading to some suggestions that Del Bosque had caved in to Chelsea's request to omit their player.
However, the 63-year-old does not agree with that assertion.
"The absence of Diego Costa is not a sign of weakness nor a sign of pride," he told the Spain national team's official website.
"The team doctors have considered that it would be counter productive to the health of Diego Costa to play these next two games. His absence allows an opportunity for other players."
Spain could risk another row with Chelsea over the use of midfielder Cesc Fabregas, who played a full match against Liverpool despite a hamstring injury.
"There is no lack of trust towards the doctors of Chelsea over Cesc," he added. "It is desirable that the Spanish doctors see Fabregas and clarify his physical condition."
