"Yes [I want him to stay], but it depends on the club, it depends on Juventus".
Olivier Giroud, Chelsea's back-up striker, has scored more goals than Higuain since his arrival.
Chelsea travel to face Czech side Slavia Prague in the first leg of their Europa League quarter-final on Thursday, and Sarri has suggested he will rotate his squad to deal with the club's busy schedule.
Hazard, who scored Chelsea FC's second goal in their 3-0 win over Brighton on Wednesday, seems to be convinced that the Blues will be able to finish in the top four this season.
"He has to improve physically, mentally, but I think also he will be able to be very useful for us in the last part of the season", Sarri said of Higuain, who has scored three goals in eight league appearances for Chelsea.
Ruben Loftus Cheek has been in sparkling form for Chelsea
"I think we have to fight until the last minute of the last match, but without looking at the other results".
Chelsea agreed an option to either loan Higuain for a further 12 months, at a cost of £15.5million, or sign him permanently for £31m at the end of his current loan, although it is unclear whether or not a Federation Internationale de Football Association transfer ban would prevent either scenario. "The situation is not clear at the moment".
"So it's not easy for a striker to play immediately well in the Premier League".
Chelsea FC will return to Premier League action on Monday night when they host bitter local rivals West Ham United at Stamford Bridge.
Asked if Chelsea must win all their remaining matches to make the top four, Sarri replied: "No, because I think the last part of the season will be really very hard for every team".
Oil eases as U.S. crude stocks build up
The market is awaiting the latest data on the US rig count at 1 p.m. - an indicator of future crude production. Weighing on prices are concerns that an economic slowdown could dent fuel consumption, traders said.