The European champions continue preparations for the defence of their title at Euro 2016 this summer with a friendly against Italy – who they beat in the 2012 final – in Udine on Thursday.
Juventus marksman Morata is bidding to be Spain's leading striker going into the tournament in France alongside Valencia's Paco Alcacer, Chelsea's Diego Costa and Athletic Bilbao's Aritz Aduriz.
But although Del Bosque is an admirer of Morata's skill set, he admits he is concerned by the forward's poor form for club and country of late.
"He has everything that is needed to be our centre-forward: physical strength, the ability to play in small or large spaces, he's strong at heading and he strikes the ball well," Del Bosque told Gazzetta dello Sport.
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"But for some reason he has not yet found the necessary regularity and it's not the fault of his coach [Massimiliano Allegri]. The player has his own responsibility.
"I don't know if he lacks belief. He is a nice guy, he's not spoiled, he is humble and quiet and this is an important thing.
"He lacks consistency in games. We hope he finds it both with Juventus and with us. He needs to appear more during games."
Former Real Madrid forward Morata, 23, has only scored once in six Spain caps and just six times in 28 Serie A games for Juventus this season.