The restricted free agent remains in his native Czech Republic while he waits to sign a new contract, reports Sportsnet's Chris Johnston.
Meanwhile, communication between the team and Pastrnak's representatives continues, Johnston adds.
Pastrnak is believed to be using an eight-year, $68-million deal recently signed by Edmonton's Leon Draisaitl as a point of comparison. His agent recently confirmed the max term has been discussed, but the Bruins appear reluctant to make him the highest-paid player on the team at this stage of his career.
The Bruins will kick off their preseason schedule Monday against Montreal.