"They are both acts of speech" is that really the best you can do? Using that logic we should also ban whispering and singing. And for the record there is quite a big difference between incitement and boycotting. Incitement encourages illegal actions such as racial discrimination or even violence. Boycotting encourages the (very much) legal action of choosing whom to do business with.
Western-backed Syrian rebels say kill foreign Islamic State (Reuters)
from the article: Israel passes law banning calls for boycott