"It was a game and in many games luck plays an important part," a surprisingly sanguine Mourinho told reporters after Real's early lead from a first minute Karim Benzema goal was overhauled by goals from Alexis Sanchez, Xavi and Cesc Fabregas.
"When we were 1-0 up we had the chance to go two up with an opening which normally with a player as fantastic as Cristiano Ronaldo would have taken, but we didn't.
"Their second came from a deflection, and no one can see it was anything other than luck. We had another chance at 2-2 and almost immediately they scored a third which was a psychological blow.
"Luck played its part but I don't want to take anything away from our opponents."
Although tempers frayed towards the end of the game there were none of the types of scenes that had blighted recent Clasicos while Mourinho, who has had outbursts against Barca, the referees and football authorities after previous matches remained calm.
When asked about a possible second yellow card Barcelona's Lionel Messi could have picked up before half-time for a late tackle on Xabi Alonso, he replied: "It was a sending off for me, but the referee was closer and could see better, so maybe it wasn't."
The Portuguese was not worried the defeat that left them level at the top with Barcelona on 37 points, though Barca have played one more game, would affect their league form.
"We are sad but relaxed," he said. "We are level on points with a game to play. As long as we don't lose this against Sevilla we will go in to the Christmas break still leaders."
His opposite number Pep Guardiola shared Mourinho's view.
"I don't think it will affect Madrid's morale. They will go away for the holiday recover and come back even stronger," he said with a very hoarse voice.
"There are still 70 odd points to play for, Madrid are still leaders, you can't say someone is already champion in November or December."
Guardiola praised his side for the way they reacted after goalkeeper Victor Valdes gifted Real the opening goal with a wayward pass after only 23 seconds.
"Valdes after his mistake continued playing the same way, making passes when many others would have started hoofing the ball down the field," he added.
"This shows his strength and our strength especially against a team who press like Madrid."
