I have a kitty that looks just like that one and she's always trying to figure out how to get to the hamster. She doesn't understand why we keep her snack in a cage where she can't get it.
They eventually get used to each other. We adopted a pet stray this summer. "Smokey" was very interested in our green cheek conure. He would leap onto Stevie's cage and watch him inside. He quickly learned Stevie can and will bite (he bit a hawk this summer who tried to carry him away). Smokey would hide on top of the cage sheet, but the bird would sneak under and around and grab his paw. That caused Smokey to start and him and the sheet would fall off the cage to the floor, which was hilarious, like watching it unfold in slow motion. Old Smoke learned fast and doesn't jump on the cage anymore. He just watches from a respectable distance...