Are there homeopathic dopamine antagonist?

No: Truly homeopathic "medications" are made by repeated dilutions, so that the ingredient is not really there anymore (just the "essence" of it remains). That means there is no active ingredient left to antagonize dopamine. However, that also implies that the homeopathic "medicine" should be pretty harmless, unless some other non-homeopathic ingredient (such as some other chemical) was added.