Saudi Arabia, the United Arab Emirates, Bahrain and Egypt imposed a boycott on Qatar three weeks ago, accusing it of backing militants - then issued an ultimatum, including demands that it shut down a Turkish military base in Doha.
Qatar denies the allegations against it and says the demands are aimed at curbing its sovereignty. A government spokesman last week said Doha was reviewing the list of demands, but did not view them as reasonable or actionable.
Gabriel told an event hosted by the European Council on Foreign Relations in Berlin that Germany remained in close touch with all sides to try to reduce tensions resulting from the biggest diplomatic crisis in the region in years. He said some of the demands being made of Qatar were negotiable, but others clearly challenged its sovereignty.
The Arab states are demanding, among other things, that Doha close Al Jazeera television, curb ties with Iran, shut a Turkish base and also pay reparations.
Gabriel said it would be tough for Qatar to accept all 13 items on what he described as “a very provocative list”.
He said efforts were under way to define which conditions Qatar could accept, and which it viewed as problematic.
Gabriel is due to meet Iranian Foreign Minister Mohamed Javad Zarif in Berlin today.
Qatar says it is being punished for straying from its neighbours’ backing for authoritarian hereditary and military rules.
In his speech in the German capital, Zarif said the countries who blamed Iran or Qatar for terrorism were trying to avoid taking responsibility for their own failures in addressing the demands of their own people.
“One day it’s Iran, today it’s Qatar,” he said. “It’s an attempt to evade responsibility, escape accountability for this very fundamental ... failure of the state system to address, to respond to the demands of its populus.”
Zarif argued for a new regional dialogue forum for the Gulf countries and called for an end to the armaments spiral in the region, which he said influenced some Western countries’ relations with states in the region.
“What is needed in our region is a regional dialogue forum,” he added.
Iran’s President Hassan Rouhani has voiced support for Qatar in its dispute with Saudi Arabia and its allies.
Crisis will not last long, says Kuwait
Kuwait’s Deputy Prime Minister and Minister of Defence Sheikh Mohamed Khaled al-Hamad al-Sabah has expressed his confidence that the Gulf dispute will end soon and it will not last long, Al Jazeera Arabic reported. During a visit to the Ali Al Salem airbase in Kuwait, Khaled said that the efforts exerted by the Emir of Kuwait Sheikh Sabah al-Ahmad al-Jaber al-Sabah will result in reconciliation among the Gulf states, stressing that the international community has expressed appreciation for Kuwait’s mediation.
