Russia, China, and Algeria, as a matter of fact.
Out of these two, at least Russia and Algeria are endorsing an alternative draft by 10 of the non-permanent members instead (unclear when that will be voted on - might be later today or pushed to next week).
Essentially, the no votes are arguing that the text uses a lot of sophistry and convoluted language to not actually impose a ceasefire and that the whole thing is a cynical US ploy to keep on giving Israel the green light.
US, OTOH, is saying it's because of politicking and language around condemning Hamas.