I could be wrong but it really isn't something that the US should ever be doing, nor any other country. Elections in theory are solely the domain of that state. For example, Russia influencing the American elections to get Trump elected was wrong.
Your position doesn't actually make sense.
Suppose country A is having an election, with candidate 1 and candidate 2. Candidate 1 says that if he's elected, country A will invade an island belonging to country B, claiming that country B won't think it's worth getting in a fight over that island. Candidate 2 says that if he's elected, country A will not invade that island, because country B will fight for it and country A will lose.
In this scenario, is it wrong for country B to announce to the citizens of country A that it will in fact vigorously defend the island? Doing so could certainly influence the election. But it's obviously not wrong. The citizens of country A are better informed in their choice because of country B's efforts.
So there's nothing automatically wrong with influencing elections in other countries. Now, there are distinctions we can draw between different kinds of influence, some of them being relevant to Russia. For example, influencing the election in another country through covert or illegal means is a hostile act against that country. My hypothetical didn't require any covert or illegal means, but Russia did use covert and illegal means in the US.
So how does this relate to Trump and Netanyahu? Well, is what Trump is doing covert? Is it illegal? No and no.
So why is it wrong? The claim that influencing elections is categorically wrong doesn't withstand even cursory scrutiny. Is there anything beyond that?