It's nearly impossible to identify as an anti-Zionist and escape charges of anti-Semitism regardless of how nuanced your views may be. Though accusations of anti-Semitism in response to critiques of Zionism are typically ridiculous, the intent behind them is far more sinister. In many cases, accusations of anti-Semitism are used in an attempt to muzzle critics of Zionism, or at the very least, to act as a barrier wall which lets critics know that moving beyond the boundaries Zionists wish to debate within must mean that you are doing so out of hatred.
One particular sort of "anti-Semitism charge" is especially troubling. It can be found everywhere, but is summed up quite nicely in the National Post by journalist David Frum. Frum quotes a comment from former interim Liberal leader Bob Rae in regard to Israeli Apartheid Week stating, "It is ... difficult to understand why this year the focus continues to be on Israel, rather than on the appalling massacres and human-rights violations that have reached intolerable heights in countries such as Syria and Iran." Frum then makes what Rae is clearly implying even more explicit by stating, "The short answer to Rae's haunting question is that anti-Israelism has never been about human rights. Anti-Israelism has always been about the destruction of one nation and one people."
I do not buy the idea that critiquing Israel instead of supposedly worse states means you are anti-Semitic, and I would like to offer a few reasons why. Primarily, there is no duty to critique every state you have a problem with, at every second of the day. This should be obvious, but Zionists seem to want their critics to follow statements like "Israel routinely violates human rights" with "and so does Saudi Arabia, Russia, Iran, etc." Most anti-Zionists I have met do have serious problems with elements of all the states mentioned, but they should not have to bring these up every time Israel is being discussed in order to somehow prove that they are not anti-Semitic.
Additionally, the fact that states like Iran have problems does not excuse Israel's own problems (just like the fact that Israel is supposedly the only democracy in the Middle East does not excuse its human rights violations). Even if one only critiqued Israel's human rights abuses, it would not make the critique any less accurate (although definitely a bit hypocritical).
Moreover, it is very difficult to find a Zionist who critiques the United Nations, and most of the western world, for not condemning Israel's entirely illegal nuclear program while at the same time harshly punishing Iran for their supposed nuclear violations. In fact, most Zionists seem to celebrate and encourage this hypocrisy, while at the same time, condemning activists for their supposed hypocrisy.
Finally, instead of it merely being OK for anti-Zionist activists to focus their efforts on Israel instead of other states, it should be encouraged in some cases. The reason is simple: many anti-Zionists, like myself, live in states that actively support Israel's problematic policies ideologically and/or financially, while at the same time harshly condemning states like Russia and Iran. Canada and the United States are two major examples of states that almost uncritically prop up Israel's violations, and as such, it should be no surprise that the number of anti-Zionist activists within these countries continues to grow.
Essentially, every anti-Zionist activist will have their own reasons for focusing their activism (often just at times) on Israel's problematic policies, and anti-Semitism does not have to be, and mostly is not, that reason. At the same time, most Zionists do not really care if their critics oppose other states or not as they just use other state's issues as scapegoats to distract from critiques of Israel.
If you do not find this convincing, try to think about how many Zionists who call-out activists for not critiquing states other than Israel genuinely care about human rights violations in states like Iran beyond using their citizens' suffering as a propaganda tool to distract attention from Israel. While it is obviously important to understand that Israel is not the cause of all, or most, problems in the Middle East, it is also important to oppose muzzling tactics from Zionists when discussing the ways Israel does contribute to broader injustices.