Morata was a second-half substitute in the 8-0 triumph.
"I am very happy because we earned a great victory and made the knockout stage easier for ourselves," said Morata. "I was a bit disappointed because I really wanted to score my first goal with the team.
"It was amazing to hear the Bernabeu chant my name. Several Castilla players have made their first team debut this season and it's great that people support us. I am a Real Madrid Castilla player and my only objective is to make good use of all the chances I get."