Los Blancos have taken 13 points from their five La Liga matches to sit top of the table, but they were held to a 1-1 draw by Villarreal on Wednesday night in a game where they fell behind.
The Madrid giants also struggled on home soil in their Champions League opener with Sporting Lisbon on September 14, and Zidane has said that his side 'cannot expect to score a late goal every game'.
"The main problem was the first half overall, we did not start the game as we should. In the first half we did not have any momentum as we did not have any intensity and didn't create many chances to score, although I cannot blame my players," Zidane told reporters.
"Of course it's impossible to be at your best from the first minute in every game and we showed that during the first 45 minutes - while defensive mistakes can happen in football. We cannot get a late goal in every game we play."
Real Madrid, who have not won the Spanish title since 2012, will attempt to continue their unbeaten start to the new season when they visit Las Palmas on Saturday night.