Targeted sanctions against an allied state can be good: they're a tool for a state to say that as as friends we won't help you with a specific thing (often an ill-advised military action). General sanctions against a non-ally can be good too, and extending the sanctions to politically-important figures makes sense (for example, Russia and oligarchs).
General sanctions against individuals where their country isn't sanctioned? That's bullying. The ICC derives its authority from its members, and if the US doesn't like that then it should take that up with the member states, not the individuals.
International politics is fuzzy enough (and the current public face of the USA is unstable enough) that it's definitely not a good idea -- but I'm tempted to say that we (as in: the UK) should draw a line and tell the US that if they want to play silly games then they're going to win silly prizes. And that if they want to sanction ICC officials (or, indeed, officials of other organisations that we participate in as a country) then they'll need to sanction the whole of the UK. It's probably a good thing I'm not a politician.