With the victory on Saturday, Croatia stays unbeaten in London and atop the group with eight points from four matches.
Miho Boskovic, Niksa Dobud and Sandro Sukno all added two goals each for Croatia, which plays Kazakhstan in its last preliminary round game.
Australia, which still has a slim chance of advancing, wraps up the group stage against Greece on Monday.
The men's field is broken into two groups of six teams. The top four from each group advance to the quarterfinals.