The 26-year-old has become an important member of Manuel Pellegrini's squad this season, making 15 appearances and scoring five goals across competitions.
His performances have attracted interest from Fulham, but Betis are understood to have set a substantial valuation before considering the possibility of a departure.
Riquelme joined the Andalusian club in a deal reported to have cost €8 million for half of his economic rights, with Atlético Madrid retaining the other half.
That arrangement is an important consideration for Betis as they assess whether a transfer would deliver a worthwhile financial return.
According to Estadio Deportivo, the club would only contemplate a sale if an offer exceeded €16 million.
Betis therefore appear determined to protect their investment in a player who has made a positive contribution during the current campaign.
Fulham's reported interest could provide an opportunity for the Spanish club to secure a significant fee, although there is no indication that an agreement has been reached or that a formal offer has been submitted.
Riquelme's form has strengthened his position at Real Betis, leaving any potential suitor facing a sizeable financial hurdle if they want to bring him to the Premier League.