Most of the designers treat interaction as any kind of communication between two or more systems. But most of the artworks we see in daily life are rather a reaction, than interaction. If all the systems provide the same output for the same input, then they can not be parts of the interaction.

Generally, to create an interaction, there should be at least one learning system (see the cover image) involved in the communication.

Also, I like the idea, that interaction could be on the mental level, on the level of exchanging ideas. For instance, when the artist makes and showcases a conceptual photo, it could become a medium of communication between the artist and the viewer.
Moreover, the artwork catalyses the thinking process and induces viewers to discuss the idea with other people.

Further reading:
— W05-3+Osman+Haque-What+is+interaction.pdf