BERLIN — The head of Gazprom, the Russian energy giant, warned European customers on Monday that if their countries angled for a single price for natural gas, it would most likely be at the higher end of the range they now pay.

In a speech in Berlin, Gazprom’s chief, Aleksei B. Miller, issued the warning as he laid out a new marketplace dynamic — one in which Russia is also looking east, particularly to China, for natural gas customers and not merely to Europe.

Russia’s new marketing outlook and the European Union’s search for alternative energy supplies have been accelerated by the Western sanctions imposed on Russia over its actions in Ukraine. China and Russia have announced plans for vast new natural gas deliveries from Siberia to China — although they have yet to agree on a price.

While a shift of Gazprom’s focus from Europe to Eurasia would very likely be many years in the making, some Europeans fear it could end up reducing vital energy supplies to the Continent.