The 20-year-old has played a key role for Croatia at the 2022 World Cup where he has started all four of their matches, including Monday's penalty shootout victory over Japan that secured his country's place in the quarter-finals.
He has also impressed for Leipzig this season, making 19 appearances in all competitions and chipping in with one goal.
Despite being under contract until June 2027, Gvardiol is attracting interest from several of Europe's biggest clubs, including Chelsea, Tottenham Hotspur and Real Madrid.
A recent report claimed that Leipzig would consider selling the defender next summer if they received a fee between £60m and £68.5m.
With Gvardiol's future at Leipzig appearing to be uncertain, his agent has indicated that the 20-year-old is satisfied with his current situation in Germany.
As per journalist Florian Plettenberg, Sisic said: "Regarding a possible transfer in summer 2023 we are not in a hurry and I can make clear that there are no pre-agreements with any clubs.
"For sure, a lot of top clubs have informed about him but Josko has a long-term contract in Leipzig. Josko feels totally happy in Leipzig. His development is amazing and RB [Leipzig] is playing very good under Marco Rose."
Gvardiol will likely feature when Croatia face Brazil in the World Cup quarter-finals on Friday.