The Welsh slumped to a 30-22 defeat in the Stadio Flaminio to record their first loss against the Azzurri in the history of the competition.
But despite his obvious disappointment the Kiwi said he had no intention of trying to coax either Scott Quinnell, Scott Gibbs or Robert Howley - all still playing club rugby - out of international retirement.
Hansen said: " If someone is retired, he is retired for all the right reasons and one of them will be because he doesn't have the desire to train and have the time commitment for what it takes to be an international player.
"The main reason we lost was because of a lack of passion. It was a lethargic performance. I cannot say why - only the players can do that. From time to time you get bad performances and we got one.
"What we do between now and Saturday will determine that and what desire and self-belief we bring. It is at times like this that you learn a man's character."