Ferrari had hoped to challenge dominant world champions Mercedes this season but have so far failed to meet expectations, with misfortune and mistakes overshadowing the opening four races.
Italian media have cast doubt on Arrivabene's tenure, while company president Sergio Marchionne has applied pressure on the team by emphasising the need for them to start winning.
"He is the best team boss I have ever had," Raikkonen, the 2007 world champion, told reporters at the Spanish Grand Prix.
"I think he is exactly the right guy for this job and he does a good job."
Vettel, the four-times world champion who joined Ferrari from Red Bull at the end of 2014, also said the former Philip Morris executive was the right man for the job.
"He is reachable, accessible for the people," said the German. "He spends a lot of time in the team, not just here but also in Maranello.
"I know there have been some rumours...but I am very, very happy he is with us and not with someone else."
Vettel, who won three races last season, was fastest in morning practice at the Circuit de Catalunya while Raikkonen was second in both sessions.
Ferrari are second overall in the championship after four races but a massive 81 points behind Mercedes.
Asked whether he felt the pressure being applied by Marchionne, Vettel said it was great to see the president so engaged.
"Of course he wants to help us where he can and of course he's upset or disappointed as much as we are when something happens that is out of your hands and we are not finishing the race," he added.
"So I see more the positives, rather than the pressure. It's good to have him behind us...this makes me actually quite confident that bit by bit things are going the right way.
"But yes, of course, we set out the target to win this year. We haven't achieved that yet so you have a fair point if you want to criticise us."
(Reporting by Alan Baldwin, editing by Ian Chadband)
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