Speaking in Berlin, Saudi Foreign Minister Adel Al-Jubeir also said efforts would be made to resolve the conflict within the Gulf Cooperation Council.
"We see Qatar as a brother state, as a partner," he told a joint press conference with German counterpart Sigmar Gabriel, according to the German simultaneous translation.
"But you have to be able to tell your friend or your brother when they are doing the right thing and when they are doing the wrong thing."
The Arab states accuse Qatar of supporting extremism, a charge Doha firmly denies.
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Jubeir said that "for many years Qatar has taken steps to support certain organisations".
"This has been condemned in the past, but unfortunately we have not received appropriate cooperation on this and that's why these measures have now been taken."
He added that "we have taken these steps in the interest of Qatar... And in the interest of security and stability in the region".
Qatar has forged regional alliances independently of its fellow GCC states, drawing accusations from Saudi Arabia and its allies of serving Iranian interests.
Gabriel said Germany "worried about the possible consequences and a growing escalation" after the "very tough" measures taken against Qatar.
Berlin's main concern was to "de-escalate the conflict" and rebuild Gulf regional cooperation, saying that "we need this cooperation in the anti-Islamic State coalition".