Behavior.xaml

<ListView IsItemClickEnabled="True" 
            ItemsSource="{Binding Items}">
    <i:Interaction.Behaviors>
        <local:ItemClickedBehavior ItemClickedCommand="{Binding ItemClickedCommand}" />
    </i:Interaction.Behaviors>
</ListView>

ItemClickedBehavior.cs

public class ItemClickedBehavior : Behavior<ListViewBase>
{
    public static readonly DependencyProperty ItemClickedCommandProperty = DependencyProperty.Register(
        "ItemClickedCommand",
        typeof(ICommand),
        typeof(ItemClickedBehavior),
        new PropertyMetadata(null));

    public ICommand ItemClickedCommand
    {
        get { return (ICommand)GetValue(ItemClickedCommandProperty); }
        set { SetValue(ItemClickedCommandProperty, value); }
    }

    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.ItemClick += OnItemClick;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        AssociatedObject.ItemClick -= OnItemClick;
    }

    private void OnItemClick(object sender, ItemClickEventArgs e)
    {
        ItemClickedCommand.Execute(e.ClickedItem);
    }
}