"I think Kimi has got to show a higher level of commitment to the process," he told reporters before the Austrian Grand Prix on Sunday.
"There are days when I think he's a bit of a laggard, but we'll see. I am going to talk to him today, we'll see what happens."
Raikkonen, the 2007 world champion with Ferrari and now 37 years old, is out of contract at the end of the season and has not won a race since he was with Lotus in 2013.
While four times champion team mate Sebastian Vettel, also out of contract at the end of the year, has won three of eight races and leads the championship by 20 points from Mercedes' Lewis Hamilton, the Finn is fifth overall.
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Raikkonen's best result of the season so far was second in Monaco in May and he finished fifth on Sunday after starting from third place. Vettel was second behind Mercedes' winner Valtteri Bottas in Austria.
Vettel, with 171 points, has scored more than twice as many as Raikkonen (83).
"Obviously I want to do well," the Finn told Reuters after the race. "I can only do the best that I can. It's not like I'm not trying. Unfortunately, it's not been very straightforward sometimes but that's part of F1.
"We keep pushing and I'm sure things will get better."
VERY SATISFIED
Marchionne said he was very satisfied with the team's performance, after a dismal 2016 season in which they failed to win a race, and also with Vettel despite the German's recent 'road rage' controversy with Britain's Hamilton.
"It's not perfect, I think we (have) still left a lot of potential gains on the track. We can make that difference up. I still think that Mercedes has a slight edge over us," said the Italian.
"I am happy with what Sebastian is doing, just in case anybody is wondering."
Vettel was handed a 10 seconds stop-and-go penalty during the race in Azerbaijan last month for deliberately banging wheels with Hamilton while they were behind the safety car.
The German was then summoned to a hearing at the sport's governing FIA (International Automobile Federation) in Paris last Monday, which decided to take no further action after Vettel apologised and accepted full responsibility.
FIA president Jean Todt said on Saturday that the Ferrari driver would face "very severe consequences" if there were any further such incidents.
(Reporting by Alan Baldwin, editing by Ken Ferris)
