The 25-year-old Hernandez, who prompted Argentina to third place in France under the guidance of Loffreda, has a year and a half remaining on his contract at Stade Francais.
But Loffreda remains eager to bring him to Welford Road to forge a mouth-watering midfield partnership with New Zealand's Aaron Mauger.
"I would like him to be here, but there are different things that don't make that possible at the moment. He has one and a half years left on his contract, but, well, who knows?" said Loffreda in the Daily Express.
Tigers chairman Peter Tom added: "We are always associated with world-class players and, with Marcelo joining us and the success in the World Cup, there was always going to be lots of speculation."