Here are a few possibilities:
1. I don't speak Italian:
* Je ne parle pas italien. (Most literal translation)
* Je ne comprends pas l'italien. (I don't understand Italian)
* Je ne sais pas parler italien. (I don't know how to speak Italian)
2. I speak another language:
* Je parle [another language]. (For example: "Je parle anglais.")
3. I speak no languages:
* Je ne parle aucune langue. (I speak no language)
* Je ne parle pas d'autres langues. (I don't speak other languages)
The best way to express the opposite of "je parle italien" depends on the specific context.