WASHINGTON (Reuters) - President Barack Obama dismissed Russia as a nation that "doesn't make anything" and said in an interview with the Economist magazine that the West needs to be "pretty firm" with China as Beijingpushes to expand its role in the world economy.

Obama has tried to focus U.S. foreign policy on Asia, a response to China's economic and military might. But for months, that "pivot" has been overshadowed by a flurry of international crises, including Russia's support for separatists in eastern Ukraine.

Russia is the world's third-largest oil producer and second-largest natural gas producer. Europe relies heavily on Russian energy exports, complicating the West's response to the Ukraine crisis.

Obama downplayed Moscow's role in the world, dismissing President Vladimir Putin as a leader causing short-term trouble for political gain that will hurt Russia in the long term.

"I do think it's important to keep perspective. Russia doesn't make anything," Obama said in the interview.

"Immigrants aren't rushing to Moscow in search of opportunity. The life expectancy of the Russian male is around 60 years old. The population is shrinking," he said.

Obama told Putin last week that he believes Russia violated the 1988 Intermediate Range Nuclear Forces treaty designed to eliminate ground-launched cruise missiles.

Speaking of Russia's "regional challenges," Obama said in the interview: "We have to make sure that they don't escalate where suddenly nuclear weapons are back in the discussion of foreign policy."

Obama described U.S. tensions with China as "manageable."

China is engaged in territorial disputes with its neighbors in the oil-rich South China Sea, and frequently skirmishes with the West over intellectual property issues.

"One thing I will say about China, though, is you also have to be pretty firm with them, because they will push as hard as they can until they meet resistance," Obama told the Economist.

"They're not sentimental, and they are not interested in abstractions. And so simple appeals to international norms are insufficient," he said.

Obama said he believes trade tensions will ease when China shifts "from simply being the low-cost manufacturer of the world" and its companies begin making higher-value items that need intellectual property protections.

"There have to be mechanisms both to be tough with them when we think that they're breaching international norms, but also to show them the potential benefits over the long term," he said.

(Reporting by Roberta Rampton; Editing by Mohammad Zargham)