The result left Real Madrid four points behind leaders FC Barcelona with 12 matches remaining. Despite the setback, Arbeloa was defiant.
"No, now we have no other objective than to win the 36 points that remain at stake. This is Real Madrid and nobody gives up here. It's a gap that we think we can close," he said.
Madrid created the clearer opportunities. Vinicius Junior raced through after a defensive mistake but was denied by David Soria, while Arda Guler also forced a save at the near post. Arbeloa felt his side had done enough to win.
"We had clearer chances than Getafe. We had Vinicius's chance, Rudiger's chance, Rodrygo's chance. We knew the kind of game we were going to play. Nothing happened that we didn't know was going to happen."
However, Getafe struck before the break. A loose clearance from Antonio Rudiger and Aurelien Tchouameni allowed Martin Satriano to volley into the top corner, ending Getafe's long scoring drought against Madrid. It proved decisive, despite late pressure from the hosts.
Arbeloa refused to criticise his players' effort.
"I can't fault my players for their commitment. The responsibility for improving our play is mine. If anyone is responsible for the defeat, it's me."
But he was furious with Franco Mastantuono, who was sent off for dissent late on and will now miss Friday's trip to Balaidos against RC Celta de Vigo.
"It's unacceptable. The Mastantuono thing cannot happen. Huijsen and Carreras' yellow cards are part of the game. But we're going to have three very important players out in Vigo."
Getafe's win was their first league victory at the Bernabeu since 2008 and strengthened their position in mid-table, moving them eight points clear of the relegation zone.
Madrid must now respond quickly. They travel to Vigo on Friday knowing that anything less than victory could allow Barcelona to extend their lead further. With a Champions League Round of 16 tie against Manchester City also looming, Arbeloa's side face a defining week in their season.
Barcelona coach Hansi Flick has made it clear his players must believe in themselves and "make the impossible possible" as they prepared to face Atletico Madrid in the second leg of their Copa del Rey semi‑final on Tuesday night.
Endrick was at the centre of the action in Ligue 1 on Sunday as his two assists helped Olympique Lyon take the lead at Stade Velodrome, yet his brilliant performance wasn't enough to prevent a 3‑2 defeat to Olympique de Marseille.
Alvaro Arbeloa has insisted his side are "very eager and focused" as Real Madrid prepare to host Getafe CF in La Liga tonight, warning that Jose Bordalas' team would pose a serious test at the Bernabeu.
Barcelona were the biggest winner in Saturday's exciting La Liga action in a day where no fixture ended goalless with crucial points collected at both ends of the league table.
