Barcelona cannot buy any more Liverpool players until 2020 unless they are prepared to pay a £90m premium on top of any transfer agreed, Sky Sports News understands.
The clause was negotiated by Liverpool's sporting director Michael Edwards during the £142m transfer of Philippe Coutinho to the Nou Camp in January.
It is an attempt to prevent the Spanish giants from poaching any more of Jurgen Klopp's talent in the near future.
The news should quell reports in Spain which have suggested Barcelona are interested in a move for Sadio Mane, who is currently involved in talks about an improved contract at Anfield.
When asked about reported interest in his best players in the summer Klopp said: "That is a good sign for the club. It is an improved situation that these players don't use us and then go. It's cool…sign your contracts but now, go again."
A number of Liverpool officials were left frustrated by Barcelona's pursuit of Coutinho, with the 26-year-old missing games at the start of last season, saying he had a bad back.
Coutinho was the subject of three failed bids from Barcelona last summer, the largest of which was worth £113m, and handed in a transfer request in an attempt to force a move.
That was unsuccessful but the two clubs reached an agreement in January, with the Brazilian signing a contract in Catalonia until the summer of 2023.