> How do you know their intentions?

Because they declared them loudly.

When they launched the drone strikes on Israel, they gave Israel and the US warning time so they could be intercepted. The second time, they gave them much less warning time.

The Iranians have a long history of negotiating loudly via their actions, which anyone who's spent any reasonable amount of time studying Iran knows and has seen in action. They're really not a mystery, they're very transparent, we just don't like what they're saying.