My dog is always trying to get to my guniea pig, why is that?

my dog sarg is 5 years old a male and is a chiauaua mix, I tried to introduce him to my guniea pig kaui by holding his mouth close and letting him sniff her but that didnt work, evry time I get up to clean the cage he jumps on the table and just stares at my guneai pig.

He might just be curious, but for extra measures I would keep them apart. It could be his hunter instincts, my dog goes nuts when he sees my sugar gliders. I hope this helps! ~Rose