Potential risks for Americans amid current Iran/Hezbollah tensions

Without the politics, probably - The danger for Americans is likely to be worse now than it was as there's always one xenophobic idiot out to blame all of any group for the actions of some, or even one, of said section of humanity.
The more your government attacks, invades, and generally messes around in other countries' politics, the greater the risk to all, that including non-Americans that look like they could be American. As an example, US embassies around the world have bigger walls and a lot more security that other countries' embassies need to bother with.
To go further, I'm often challenged and asked if I'm American but, once I tell them I'm not, things immediately calm down. I probably notice more than other expats as I travel a lot in places expats tend not to go. That applies to Malaysia and Indonesia - I can't be as sure for Lebanon, but I suspect it's about the same.

Your government's travel advisory is here

https://travel.state.gov/content/travel … isory.html

As far as Lebanon is concerned, the advisory is spot on.   There are some places where you shouldn't advertise the fact that you are an American and Lebanon, nowadays, is one of them.   

It helps to be an American in parts of the Arab world like the GCC where you will get preferential treatment but not so much in others.

Stay in places to know. Have a few thousand dollars set aside for evacuation should you need to. This is how I would stay safe in Lebanon.

Also be careful who you are dealing with due to the potential of US sanctions.

Otherwise in my personal experience, I have met Americans in Lebanon and they seemed to be doing fine, I have not see any hatred. However they were hanging out in relatively cosmopolitan spots.