No. The government has a plan, decides who should get the (limited) vaccine when, and by rejecting you are going against it. Even if it's not the government you voted for, sabotaging the initiative is wrong. That said, I haven't decided if I'll actually show up for my jab this Thursday.
Well, I haven't been offered vaccine by the government here, but as I understand it, the government plan is not to force people to take it. The government plan is to offer it to whoever they want and can at every moment. They want to offer to those more at risk, basically, with criteria they can handle, so it boils down to medical personnel (+ some notion of essential workers) and age groups more or less.
If the citizen says no, that's not sabotage, that's just information that the government can give the dose to someone else. Then I'm not sure what's the plan if that same citizen at a later time decides to take the vaccine. Maybe they give it or there's some (long?) wait time or...
There can be a lot of reasons to say no. Maybe you want the vaccine but you don't want to sign the document they have you sign. Maybe you want to move elsewhere in a few weeks and prefer to have both doses there...
Maybe you want to wait until they can ensure they'll give you the second dose at the delay tested in the trials and not some improvised plan with expert input but no trial yet...
I've only known of fines for not taking vaccines in Galiza, stated but not used yet, and I believe the law is still contested in the courts.
Sabotage would be something like I heard happened in Israel, where citizens who had an appointment didn't show up and they had to destroy vaccine doses because they were too long outside freezers or something.
But as long as you don't agree to an appointment or you cancel it soon enough that they can call someone else you're not sabotaging anything (beyond your own health, depending on your own opinion).
Now, if you're just undecided and prefer to think you're forced, to untie the decision, then I'd better say nothing.
But I don't know your situation in your place with your government, maybe you should ask before doing something if you really feel forced. At least confirm you are forced to do it, if you really don't want to do it.
I think the difference is in whether you think the government plan is offering vaccines or vaccinating. Rejecting a recommendation is not rejecting an order (and then there're the ethics of governments ordering people to take drugs, which one would have to consider when considering the ethics of citizens refusing government orders). From what I heard from people vaccinating there's a consent paper people have to sign. That proofs it's not an obligation, because then the signature would be invalid (not freely given).
In any case, if you can't decide what to do this weekend, then just go and take the vaccine, it won't kill you more than anyone else, and cancelling an appointment hours before the fact is quite unpolite.