Basically. Strong country attacks weak country. Weak country can't fight back against strong country so they attack other weak countries hoping they can get enough negative feedback to strong country. And seek sympathy from people in strong country.
Saudi and Iran hatred goes back long before that. Shia vs Sunni. Genesis of most of the problems in middle east. Syrian civil war: Sunni vs Alawites(Shia offshoot). Yemen civil war: Sunni vs Shia. When a mosque is bombed somewhere in middle east, its sunni vs Shia. It makes for some interesting decisions on support from the US side. We are now backing the new president of Syria who spent had spent a decade killing Americans in Iraq when he was leadership in Iraqi Al Qaeda.
Why would they want to harm Iraq? Iraq is mostly Shia who identity with Iran. Their only real military force is Iranian backed Shia militias which led to some interesting things like US bombing Iraqi military installations. More interesting is the media never covered all the American A10s strafing Iraq government installations in Iraq.