Asked if he has considered offering his resignation, Rijkaard added: "This is not the moment to talk about it."
Bojan Krkic and Samuel Eto'o had Barca 2-0 ahead before Betis stormed back through efforts from Juanito and a brace from Edu.
"I believe that we had the players on the field who knew exactly what was needed to dominate the opponent away from home," said Rijkaard. "I do not want to use the word 'relaxation' because it is inexplicable that we have fallen into this trap. I have few words to explain a 3-2 defeat.
"It was one very hard night. Right now, we've lost a game that seemed easy. This defeat does not deserve more words."
