Sarri's preference is to be reunited with Higuain - who enjoyed his most prolific ever season under the Italian - though any deal is complicated by the forward now being on loan at AC Milan from Juventus.
"He has to make a decision and take on his share of the responsibility", said Leo.
Higuain had his most successful season under Sarri, breaking the Serie A goalscoring record with 36 goals in the 2015/16 campaign.
Brazilian Leonardo added: "There's no point following rumours and gossip".
"He is here right now".
Higuain's had a nightmare term thus far.
The 26-yer-old Spaniard has struggled for form since his £65m arrival at Stamford Bridge from Real Madrid in 2017.
Despite a strong start to the season, Chelsea have faded in the Premier League title race and Higuain could be the first of several new faces to join the club in the January transfer window.
The Blues are not keen to negotiate with two different sides, and will look elsewhere for another option to compete with Olivier Giroud and Alvaro Morata.
As well as Higuain, Chelsea are believed to be keeping tabs on Bournemouth's Callum Wilson, who was a reported £50 million price tag.