From the Oxford dictionary:
sour grapes
used to refer to an attitude in which someone adopts a negative attitude to something because they cannot have it themselves:
government officials dismissed many of the complaints as sour grapes
Is there an equivalent or similar expression in Spanish?
The precise translation may vary depending on the context, but envidia captures the meaning of sour grapes; take a look at the definition according to the DRAE:
envidia.
(Del lat. invidĭa).
f. Tristeza o pesar del bien ajeno.
f. Emulación, deseo de algo que no se posee.
In your concrete example, I would say something like:
Los representantes del gobierno rechazaron la mayoría de las quejas por considerarlas producto de la envidia.
My Larousse Gran Diccionario translates it this way:
IDIOM it's (a case of) sour grapes es cuestión de despecho
So there may not be an equivalent idiom, or at least not a widely used one.
Apart from "envidia" given by Gonzalo Medina, maybe "frustración" can also match the meaning:
El gobierno desestimó muchas de las quejas por ser producto de la frustración.
There is an Esopo's fable about the fox that passes by a grape vine. There were a bunch of grapes that looked simply delicious... and the fox was hungry. So he jumped and jumped trying to get them, effortlessly. Finally he gave up saying: "They are not ripe yet!". In Spanish the fox said: "¡Están verdes!", or very well could have said "Sour grapes!"
So this could be a good translation: "Están verdes". However, even though valid and used, it's not really widely used.
I think this idiom comes from the Aesop's fable The Fox and the Grapes http://en.wikipedia.org/wiki/The_Fox_and_the_Grapes. Thus, the most exact (but not necessarily the best) translation would be "uvas verdes", which refers to the same frustration feeling. Please note that it is not a spanish expression in common use.
Could you say ¡qué envidia! (like you all would say ¡qué lastima!), or something like that?
