Anti-Semitism is a fear or hatred of Jews. Anti-Zionism is fear or hatred of a Jewish state, particularly Israel.
The question: is it possible to be anti-Zionist without being anti-Semitic?
I think it is but, depending on your terms, it may be quite difficult and there is so much overlap between the two it may be difficult to distinguish one from the other. I think that Gulf Arabs tend to be both anti-Zionist and anti-Semitic.
I am most definitely not anti-Semitic; if anything I’m philo-Semitic. I also do not think I’m anti-Zionist. Rather I am indifferent to the state of Israel and hold the view, out-of-step for an American, that Israel is a state just as Russia, China, or Saudi Arabia are. The people who created the state of Israel do so in the way most states did: they took it by force of arms and the Israelis will keep it as long as they can do so by force of arms. Israel has its interests; we have ours. Sometimes those interests coincide; sometimes they conflict; sometimes we just don’t give a darn.
I am uneasy when we pursue Israel’s interests uncritically just as I am when we pursue the United Kingdom’s or Germany’s interests, particularly when they do not coincide with our own. I don’t think that makes me an anti-Semite.