I don't think parsley.js meant to work directly with KnockoutJs, but this can't stop you from using them both nicely.
Quick look through the Documentation -> Javascript - > Form you can use this method:
$('#form').parsley('isValid');
Useful if you want to integrate the form validation process inside custom functions, without triggering error messages.
UPDATE
you can try this too:
$( '#form' ).parsley( 'validate' );
Useful if you want to integrate the form validation process inside custom functions.