The 62-year-old insists including the in-form Atletico Madrid attacker - if he does change allegiance - is an option he would take but does not want to disrupt the squad's harmony
The international future of Costa has come under scrutiny in recent weeks as the Selecao seem hesitant to call up the 25-year old, despite him scoring 10 goals in only eight starts for Atleti this season.
And though Del Bosque is keen on adding the player to his already talented squad, he does not want to upset other strikers that he could call upon, such as Premier League duo Roberto Soldado and Alvaro Negredo, as well as Spain's record goalscorer David Villa.
"We are obliged to have a conversation with him," Del Bosque told TVE. "He's in a difficult situation because Brazil also want to have him and he has to decide in the coming weeks.
"It's very difficult to please everyone, but calling up Diego Costa is no disrespect to the others."
Del Bosque was also quizzed on the debate over who should line up in goal for Spain at the World Cup among Iker Casillas, Victor Valdes and Pepe Reina but refused to say who was his preferred option and touted Manchester United goalkeeper David de Gea as possible future Roja star.
"We'll see what happens in each situation," he told reporters.
"The three of them are all over 30 years old. David de Gea is playing in a great team and we have high hopes for him."
Spain secured their place at the World Cup next year, finishing top of Group I in World Cup qualifying, three points ahead of France who will now be forced to qualify via a play-off.