It was the first game for Barca since the resignation of president Josep Maria Bartomeu.
Roberto said: "We are very happy, especially for scoring. Being with six points is important. It has only been two goals but we could have scored more.
"The important thing is to make chances. If we continue like this, the results will be more consistent. After the defeat against Madrid, it was important to score.
"We must continue in this line."