No, they are claiming they eroded vital government services, not civil rights. Indeed, civil rights isn't mentioned at all in your link. Perhaps your algorithm had a false positive from the phrase "civil servants" which is in the article? Get your programmer to check that before you post more links, okay?
Oh well, our government has some ideas to erode civil rights as well, namely with a bill on public safety. However, according to that link, those protesters were "Marching for Dignity" and against a government that has eroded "Spain's much-valued public health and education systems". Also, they were protesting against corruption, evictions, high unemployment and the lack of opportunities that makes young people to emigrate.
Whereas the bulk of the march was peaceful, there were clashes between a some group of "infiltrated" or "radical elements" and a group of policemen that found itself isolated from the rest of the police force, with the result of more than 50 wounded agents. The right-wing press took advantage to say the march was a violent demonstration by the far-left and some police unions criticised police commanders, because they think the deployment was badly planned and nobody ordered to help in time the policemen under attack. Such controversy follows another triggered by an incident in the Morocco border, when 15 African immigrants died while trying to reach the town of Ceuta, a Spanish enclave in the south shore of the Gibraltar Strait. Apparently someone ordered security forces to shot plastic bullets against the immigrants, but nobody knows who.
