I used this greek dictionary along with wiktionary. http://www.greek-language.gr/greekLang/modern_greek/tools/lexica/triantafyllides/
Thanks, Dimitra. I don't know if this helps, but αμφιβάλλω also had (ancient Gk) the nuance of "throwing from all sides," that is, "cast," and was used as a fishing term alongside αμφίβληστρον, a casting-net (for fishing); an αμφιβολεύς was a man who fishes with an αμφίβληστρον. Since αμφιβάλλω had the sense of throwing/casting all around, it could be used to refer to "embrace" (LJSM, 89). Your point about "hitting" on all sides is helpful (cf. LJSM 89), and clearly also leads to the sense in context of "doubt" in antiquity. It makes sense to me that an idea that "hits" on both sides and is "cast" all around would cause doubt. The NT uses the verb διστάζω for "to doubt, waver" and does not use the noun αμφιβολία, which in antiquity could have the sense of ambiguity (LJSM, 90). It's helpful and interesting to learn that αμφιβολία no longer has that sense (jaye16 below).
According to Google Translate, the English word "ambivalence" in Greek is "αμφιβολία". Is there some other word you know in Greek that means ambivalence? If not, given only the Greek we have no reason to prefer one of these English words over the other.
And while ambivalence literally means "have two feelings", it is commonly used to indicate uncertainty in choosing a course of action, as is doubt. So even if there were more context it might not be clear which is intended, though it is certainly possible to imagine a specific context where the distinction could not be doubted.
I wouldn't trust Google translate especially for Greek and especially for anything more than a general indication of meaning. It's better using a dictionary for exact translations.
I'd translate ambivalence as αμφιταλάντευση, which fits right in with the etymology of ambivalence as well. (BTW it's a lot more likely that you'll hear the verb, αμφιταλαντεύομαι.) Sure there's overlap with doubt, but replacing one word with the other takes a bit more than that. :)
This is a compilation of 7 dictionaries.