Most of Iran's violent actions were done by proxies, exactly as happened in this case. I provided multiple Wikipedia links with sources showing how these proxies are armed and directed by Iran.

Here's another article about their military activity in Iraq: https://en.wikipedia.org/wiki/Iranian_intervention_in_Iraq_(...

Besides that, they have been involved recently in multiple actions to seize oil tankers, culminating in the seizure of a British-flagged tanker:

https://www.nytimes.com/2019/07/20/world/middleeast/iran-tan...

They seized other tankers as well, for instance:

https://www.bbc.com/news/world-middle-east-49225916