From the Wikipedia article

> Inverse surveillance is a subset of sousveillance with a particular emphasis on the "watchful vigilance from underneath...

No. Sousveillance is possible without intent to observe the surveillance mechanisms in place. Go to a festival, these days, with the plethora of cameras (on phones or standalone, video or still) and people are participating in sousveillance (though likely not deliberately or recognizing it as such). They aren't watching the police or other observers. They're just particpating and recording the event itself.