Barca might have been more comfortable had Robert Lewandowski not ballooned a first half penalty over the bar at the partially rebuilt Camp Nou.
"It's football -- after going in a good dynamic we've had some results we don't like, but we know what we want," Alonso told reporters.
Barcelona beat Athletic Bilbao 4-0.
Teenager Lamine Yamal also scored for Barca.
Ferran Torres was also on target for the Catalan giants, who moved back into second place to trail leaders Real Madrid by five points.
The rivalry is beyond football. It’s culture. It’s philosophy.
After rivals Barcelona briefly displaced Los Blancos with a narrow win over Girona on Saturday, Xabi Alonso's side restored their two-point advantage before next weekend's Clasico.
Los Blancos moved two points clear of champions Barcelona, who visit Sevilla on Sunday, as they bounced back from last week's derby drubbing.
Julian Alvarez struck twice to earn Atletico Madrid an emphatic 5-2 derby victory over LaLiga leaders Real Madrid on Saturday, ending their rivals' perfect start to the season.
After rivals Barcelona briefly displaced Los Blancos with a narrow win over Girona on Saturday, Xabi Alonso's side restored their two-point advantage before next weekend's Clasico.
Los Blancos moved two points clear of champions Barcelona, who visit Sevilla on Sunday, as they bounced back from last week's derby drubbing.
Julian Alvarez struck twice to earn Atletico Madrid an emphatic 5-2 derby victory over LaLiga leaders Real Madrid on Saturday, ending their rivals' perfect start to the season.
Despite missing star winger Lamine Yamal, Barca recorded their fourth consecutive victory across all competitions without the teenager.
The win keeps the unbeaten Catalans second in the standings with 13 points, trailing leaders Real Madrid by two points.
Madrid are five points clear of second-place champions Barcelona, who host Getafe on Sunday.
Xabi Alonso's side top the table on 12 points from four games, three ahead of second-placed Athletic Bilbao after they fell 1-0 against Alaves to tarnish their own perfect start.
The veteran Polish forward, 36, reached 27 league goals for the season, although he finished behind Real Madrid's Kylian Mbappe on 31.
The Italian tactician, normally a picture of sideline serenity, could only shake his head as his injury-ravaged defense struggled against Barcelona's relentless assault at a sold-out Montjuic Olympic Stadium.
Paris Saint Germain head coach Luis Enrique made a bold prediction about tonight’s El Clasico in La Liga between Barcelona and Real Madrid, saying the Catalan Giants will easily defeat their arch nemesis.
