Why did countries such as France and Austria not want a unified Italy?

The main reason for this is that Austria owned parts of
the territory that is now Italy.  Because of this, they did not want Italy to unify as
that would have deprived them of their territory.

For
example, the Austrians were in possession of two major parts of Italy.  These were the
provinces of Lombardy and Venetia , both in the northern part of what is now Italy. 
From these provinces, Austria was able to dominate politics in the whole
peninsula.

By the time Italy was starting to truly unify,
France was also afraid of a strong Italy.  It did not want a unified country that would
be a major danger to it.  A disunited and weakened Italy was much more to France's
liking.

So, France and Austria opposed a strong and united
Italy because it would potentially be a danger to France and because it would take
territory from Austria