The Tykes, who have already signed former Irons Paul Hayes and Richard Kell this summer, have offered a contract to the out of contract Wrexham striker who hit 22 goals last term.
But the player, who moved to Britain to support Liverpool striker Xabi Alonso, looks set to join Crewe or Coventry.
Tykes boss Andy Ritchie said: "We made an offer to Juan and his agent spoke to us this morning.
"It was a positive reply but the player wants to test himself at Championship level and I know that Crewe Alexandra and Coventry City are interested.
"His agent also told me that Juan would be still interested in a move to Oakwell if nothing came from the Championship."