It took a second half equaliser from Karim Benzema to earn Madrid a point, and Zidane was far from happy with the opening 45 minutes.
"I didn't like what I saw in the first half," he said.
"The second was much better.
"We can do much more. The sensation [from the match] isn't good, but it's not bad either because we drew against a team that don't give much away [at Butarque]."
Gareth Bale was left on the bench again, adding fuel to the fire of reports that his time in the Spanish capital is set to end this summer.
"You can ask about Bale every day and I'll answer the same way," he began, "he's a big player in the squad.
"I wanted to make changes today and that's it.
"Playing for just a few minutes, as is the case for Lucas [Vazquez], is complicated."