Higuain is now on loan at AC Milan, but the 31-year-old has struggled for form, with just eight goals in 20 appearances this season.
The Argentina worldwide has been linked with a move in the January transfer window, with Chelsea reportedly keen.
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, ' Leonardo said at a press conference on Tuesday.
Higuain poised to end AC Milan loan to join Chelsea
Higuain had his most successful season under Sarri, breaking the Serie A goalscoring record with 36 goals in the 2015/16 campaign.
"Gonzalo has lived through this moment but now he has to leave it behind him".
"But with all the rumours, there is no point in me thinking about these different situations until we have something to answer". Seeing as he is here, he needs to get down and actually do something for this team. He's only netted six goals in the league as he struggles for form.
"What we do know is that Chelsea absolutely - I won't say desperate - but they really, really need a striker".
His arrival would likely signal the departure from Chelsea of Alvaro Morata, with Sevilla keen on bringing the misfiring striker back to Spain.
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