La Real were good value for the three points, though Barca's players were left furious with the officiating of Gil Manzano.
Skipper for the day, De Jong said: "I think we deserved to win today. We had many chances, but we had to convert them. We played well; it's just that we didn't win.
"We lacked the finishing touch. Their goalkeeper had a very good game."
Then on Gil Manzano, the Dutchman fumed after Lamine Yamal's goal was ruled out for offside: "In the end, if it's offside, it's offside. There's no other way. I didn't see it. We were told it wasn't. Then I mentioned it to the fourth official. Something exactly the same happened here last year.
"What I do want to say is that you can't even talk to the referee. I'm the captain and I don't understand it. He looks at me with a face like, 'I'm better than you.' It's frustrating. He can't behave like that."
He also stated: "We missed so many chances. It's the most disappointing thing. At the end of the game, in stoppage time, I kept telling him to keep an eye on the clock.
"They take a minute to take the goal kick... it's normal for them to do that. And he didn't even give ten more seconds. It's crazy. I told him that and he gave me a card."