The Finn returned to Ferrari from Lotus for this year and has struggled to match team-mate Fernando Alonso so far.
Raikkonen has found the handling of his F14 T difficult in the early races and sits 12th in the drivers' championship with only 11 points compared to third-placed Alonso's 41.
Raikkonen trailed home eighth in the Chinese Grand Prix on Sunday, complaining of a lack of grip, while Alonso recorded the Scuderia's first podium of this campaign.
Chinese GP analysis: How team-mate wars were won
Raikkonen fired back at reporters when it was suggested his motivation might be suffering as a result of his disappointing start to 2014.
"I don't know why you always come up with motivation - if I didn't have motivation I wouldn't be here," said Raikkonen.
"It's f**k all to do with this.
"We have bad races and it's an unfortunate thing, but that's how it goes sometimes. The aim is to improve.
"There's a lot of work to do. We haven't had a single race where we've been happy with everything.
"Things have been difficult so far, but once we get more mileage we can work things out."
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