Saudi Arabia, the UAE, Bahrain and Egypt accuse Qatar of supporting extremism and of being too close to Iran, which Doha has strongly denied.
German Foreign Minister Sigmar Gabriel, who on Monday starts a tour of several Arab states, called for a "serious dialogue" to end the crisis following the de facto blockade of Qatar by its neighbors, AFP reported.
"Since many weeks, the brotherly countries and neighbors of the Arabian peninsula have been locked in a conflict that has fuelled concern," Gabriel said in a statement.
"We are worried that the distrust and the disunity could weaken all the parties concerned as well as the entire peninsula," said Gabriel, who will visit Saudi Arabia, the United Arab Emirates and Qatar.
Gabriel called for a "serious dialogue between the parties" to resolve the crisis, adding that while Berlin was "not taking sides, the conflict... affects both us and our interests."
"This is true of the fight against the Daesh (also known as ISIL or ISIS) but also for the stability of a region that has been particularly marked by crises, tensions and war."