Sergio Marchionne has issued a wake-up call to Kimi Raikkonen.
However, the Ferrari president also rejected rumours that Max Verstappen or Fernando Alonso are in the running to replace him.
"We have not reached out to Red Bull about Verstappen and we are not interested in Alonso," Marchionne was quoted as saying in Austria.
"We have received some suggestions about Alonso's return, but we have two good drivers.
"So we are not interested - it is not possible for now for Fernando to come."
Sebastian Vettel's contract is also up at the end of the year, but Marchionne said that the Maranello team are happy with the 2017 championship leader.
As for the German's teammate Raikkonen, the Italian-Canadian is quoted as saying by La Gazzetta dello Sport: "He is a good guy and he is working, but we need him to [help to] win the constructors' championship."
Finnish broadcaster C More also quoted Marchionne as saying: "I think Kimi has to show a higher level of commitment to the process.
"There are some days when he is a little sluggish, but we'll see."
Finland's Ilta Sanomat quoted Raikkonen as responding to Marchionne's 'wake-up call': "I would of course prefer better results but I cannot do any more than my best.
"Unfortunately in formula one, everything does not always go as expected."
Marchionne said that Ferrari will not "think about the drivers" for 2018 "until September", which ties in with Alonso's own timetable for his plans for next year.
"We have a world championship at stake and we want to arrive at the end of the season with the position we have now in the standings," Marchionne insisted.
The 2017 season continues on Sunday with the British Grand Prix.
