The former Real Madrid boss lamented his side losing the match but stated he was happy with what his players showed after the interval
The European and world champions got off on the wrong foot and conceded a goal in the opening quarter from Riccardo Montolivo, but restored parity thanks to a Xabi Alonso penalty.
A late Alberto Aquilani strike gave Italy the victory, however, in front of their own supporters in Bari, and Del Bosque blamed Spain's poor start to the match for the result.
"We started out really shy," he said after the match. "I am really happy with the second-half, though. Generally speaking, this was a good match.
"But in the second-half, when we had improved, the defeat happened."
With injuries to Fernando Torres, Gerard Pique and Andoni Iraola, the Spain coach also added that the match was no ordinary encounter.
He added: "We made a great effort, under circumstances which are not normal."