It's particularly challenging for people Iran might deem to have Iranian nationality (dual nationals obviously, but also people who were formerly or are eligibl

It's particularly challenging for people Iran might deem to have Iranian nationality (dual nationals obviously, but also people who were formerly or are eligible for Iranian citizenship but don't currently claim it), but otherwise a lot of the restrictions are more "our government doesn't like their government and wants to reduce trade", not actual safety risk to individuals. Unlike NK, Iran has generally not detained purely US persons who were on group tours. If there were some flare-up in tensions, sure, you could become a diplomatic problem, but otherwise it's probably safer than many other countries as a visitor.