It's surprisingly difficult to find ships if they don't want to be found. Iran has been able to maintain it's shadow fleet for decades for a reason. It'd be more difficult to get a boat that close to the USA for sure, but not impossible. What is more likely are attacks by the various Iranian terrorist organisatons that have been showing up especially in the UK [1, 2].

[1] https://news.sky.com/story/four-arrested-on-suspicion-of-syp...

[2] https://www.jpost.com/diaspora/antisemitism/article-890851