However, the Portuguese added that he felt more positive about the performance than Sunday's shock 1-0 defeat at Levante and urged his players to get back to winning ways at home to city neighbours Rayo Vallecano this weekend.
"We've dropped five points in two away games and that is worrisome," the former Inter Milan and Chelsea manager told a news conference.
"But it's less worrying to draw a match in which you're the only side that tries to play and win," he added.
"We've scored one goal in our last three games and we must return to normality by scoring and winning on Saturday."
Real lacked the zip and zest that inspired them to a 6-0 win at Real Zaragoza in their opening match of the campaign, as they bid to end Barcelona's three-year grip on the Spanish title.
Former World Player of the Year Cristiano Ronaldo, who sustained a gashed ankle in Champions League action last week, looked well below his best and Mesut Ozil, often the creative spark of the side, was largely anonymous.
"As a team we didn't do our best and some of our players performed under par," Mourinho said.
"Our concentration was better tonight than it was on Sunday and I have a different overall feeling about the game."
Ahead of Barcelona's later match at Valencia, Mourinho aded: "Our main reference in terms of fighting for the title is Barcelona and if they win tonight they'll only have a three-point cushion over us, not a 30-point lead."
There was some comfort for Mourinho and his players as Barca twice had to come from behind to rescue a point at early pace-setters Valencia.
With four games played, Valencia lead with 10 points, Barca are fourth on eight and Real are seventh with seven.
