I think if you read this excellent historical novel carefully, you can clearly see that Dickens, whilst he feels sympathy for the French peasants that bore so much oppression and injustice for so long, never condones the violent steps they took. He clearly portrays the aristocracy of France as being ruthless, greedy and unsympathetic characters, but he likewise portrays the violence of the Revolution in all of its horror, condoning neither.
Note the way that Monseigneur in Book II Chapter Seven is described in all of his luxury and wealth:
Monseigneur was in his inner room, his sanctuary of sanctuaries, the Holiest of Holiests to the crowd of worshippers in teh suite of rooms without. Monseigneur was about to take his chocolate. Monseigneur could swalllow a great many things with ease, and was by some few sullen minds supposed to be rather rapidly swallowing France...
Note the irony in this passage, where the aristocracy are presented as "swallowing France" and using all the wealth for foolish, frivolous purposes whilst the peasants starve and struggle with hardship. Clearly the aristocracy are not presented in a sympathetic light.
However, note the description of the peasants of the Revolution in Book III Chapter 2, where the violence of the Revolution is described in its full gore at the grindstone:
As these ruffians turned and turned, their matted locks now flung forward over their eyes, now flung backward over their necks, some women held wine to their mouths that they might drink; and what with dropping blood, and what with dropping wine, and what with teh stream of sparks struck out of the stone, all their wicked atmosphere seemed gore and fire. The eye could not detect one creature in teh group free from the smear of blood.
The use of words such as "wicked" and "gore" clearly show the abhorrence that Dickens feels towards the revolutionary force that took such extreme measures against their injustice.
So I think that if you look at the novel, Dickens definitely does not support the cruelty and luxurious waste of the aristocracy, but neither does he support the violent measures taken by the peasants to overthrow the aristocracy.