Barcelona has been able to sign players despite a so-called "transfer ban", but has been unable to register said players until the ban is over. What this means is Arda Turan, signed from Atletico Madrid, and Aleix Vidal, signed from Sevilla, cannot play for the club until January.
Apparently, this extends to even friendlies as well, because the ban is for any match with a referee's report.
This means fans attending the USA tour, fans in Italy for the Fiorentina friendly, and fans at the Joan Gamper match won't get to see the newest additions to the blaugrana club.
Barcelona consulted FIFA directly on the matter, but FIFA said no, according to Spanish radio station Cope.