"We had a disappointing performance in our last game. We need to reflect on our mistakes and make improvements in order to get back on track and start winning again," Raphinha told Movistar.
"We lowered the level we were playing at and that is making games hard for us. We have to keep working and improve...
"I don't care about my goal, I care about winning, we didn't win and I'm not satisfied with the game."
Barcelona wore white shorts as part of their anniversary celebrations, as they used to back at the start of their history.
They held a gala in the city on Friday night to mark the occasion, having been founded on November 29, 1899, but came undone on Saturday afternoon.
"We have to (play) like we did at the beginning of the season... it's a big disappointment today," Flick told reporters.
Advertisement
"Today we have more than 70 percent ball possession but we're not able to score the goals -- maybe we have to change one or two things.
"We made some mistakes, but it was not the back four, it starts (with the players) in front, we have to speak about that."
The Catalans were able to name teenage starlet Lamine Yamal on the bench after recovering from an ankle problem.
Former Barcelona goalkeeper Jasper Cillessen made a solid save to deny Fermin Lopez in the opening stages, with Las Palmas showing enterprise on the counter-attack.
Advertisement
Barca defender Alejandro Balde was forced off with concussion in the first half after a clash with Sandro, to be replaced by Gerard Martin.
Las Palmas came close when Alberto Moleiro teed up Javi Munoz, who drilled wide, while Jules Kounde lashed an effort over at the other end.
Raphinha came closest to breaking the deadlock in the first half, scoring from an offside position, after Cillessen denied Pedri, and hitting the crossbar after being played through by Gavi.
Flick threw on Yamal at the break for Pablo Torre, hoping the winger would give Barca the advantage after an even first half.
Las Palmas took a surprise lead early in the second half when Kirian Rodriguez played in Ramirez, who drilled home from the edge of the box.
Raphinha hit back quickly for Barcelona with a thumping long-range effort, but Las Palmas were soon ahead again.
Silva ran onto Munoz's probing long ball and fired past Inaki Pena to restore the Canary Islanders' advantage with his fifth goal in eight league matches.
Cillessen saved well to deny Yamal as Barca sought a leveller and Viti made a brave block to thwart Pedri.
Las Palmas survived eight minutes of stoppage time, with Dutch stopper Cillessen again saving from Yamal and two defenders desperately scrambling to block a late Robert Lewandowski chance to lock in the visitors' victory.
"It was a very important win, we worked hard for it, Barca put you under a lot of pressure," midfielder Moleiro told Movistar after Las Palmas sealed their first away win at Barcelona since 1971.
Since coach Diego Martinez's arrival in October when they were bottom, the minnows have improved drastically and this win helped them climb five points clear of the relegation zone.
Listen to the latest songs, only on JioSaavn.com
"Everyone is giving their all, and that's the key," added Moleiro.
(This story has not been edited by staff and is auto-generated from a syndicated feed.)