Vice-president Vadim Vasilyev and Jardim have previously been clear that Lemar and other Monaco stars including Fabinho will not be allowed to leave mid-season.
Kylian Mbappe, Bernardo Silva and Benjamin Mendy all departed last season's Ligue 1 champion, which sits second in the table, nine points behind Mbappe's new side Paris Saint-Germain.
Lemar was close to joining Arsenal on deadline day only for the move to fall through, scuppering Alexis Sanchez's planned switch to Manchester City in the process.
The versatile France international has also been linked with Liverpool, which is seeking replacements for key midfielder Philippe Coutinho after he sealed a dream move to Barcelona.
Jardim stressed again that Monaco do not typically sell players in the January transfer window, but the coach understands a large bid for Lemar would give his side a decision to make.
"We are not used to selling in the winter," Jardim said.
"But the transfer window lasts until the end of the month and many things can happen."
Jardim suggested fringe players could be allowed to follow Terence Kongolo and Souahilo Meite by leaving Monaco on loan.
"Maybe a few who play little will be able to find time for play," Jardim said.
Lemar has been included in Monaco's squad for Wednesday's (NZDT) Coupe de la Ligue quarter-final at Nice, but striker Radamel Falcao is out with a calf injury.