LA FC will make their debut in the MLS in two years' time and, despite Rooney's reported desire to stay at United, Penn revealed the forward is one of a number of players the club is currently targeting as they look to assemble their first-team squad.
"Wayne Rooney is an example of the calibre of player we are looking to bring to LA FC," Penn told ESPN FC.
"He is one of 10 names we are looking at, but we are a long way from signing anybody up right now.
"We are still 18 months away from our first MLS game, so we will see if players of Rooney's status and reputation are interested.
"But LA FC is a club with the ambition to match its surroundings, so it is important for us to attract players with a global reputation."