What is this little owl-like bird?
This looks a lot like a double-barred finch (Taeniopygia bichenovii). Your note about this being an "owl-like" bird is supported by it's less common name, the "owl finch", so named for the dark ring around the face. 



 Source: Wikipedia; Credit: Glen Fergus 

If this is in fact the bird you saw, you're right that it's not native to your country (or continent or even hemisphere!). The Taeniopygia genus is in the Estrildidae family, and it only contains two species native to Australia! According to Wikipedia, T. bichenovii is found:


  in dry savannah, tropical (lowland) dry grassland and shrubland habitats in northern and eastern Australia


You can read more at eFinch and The Atlas iof Living Australia.