The Russian energy minister, Alexander Novak, said his country’s output, 11.4 million barrels a day in October, would be reduced by around 230,000 barrels.

Chris Midgley, global director of analytics for S&P Global Platts, which tracks energy and commodities markets, said the deal reflected “sensible diplomacy” by the Saudis in the face of American pressure. “They look to Russia to get involved,” he said. “It takes some of the focus off them.”

Over the summer and fall, the Saudis and Russia ramped up production quickly in response to pressure from Mr. Trump and to ease market anxiety over the potential drying up of supplies because of Washington’s reimposition of sanctions on Iran. In November, Saudi output reached an unusually high level of 11.1 million barrels a day.

Mr. Falih said the producers group could “swing both ways.” With growing concerns about oversupply, he said, it was natural to take crude off the market to avoid “a glut that brings havoc” to the oil industry.

In the past, the Saudis have tried to avoid being the swing producer, the oil power that adds and subtracts supplies according to market pressures. At the moment, though, they seem more or less stuck with that role.

In two days of difficult negotiations, the Saudis pushed for all OPEC members to join in the cuts. In the end, though, the group granted exemptions to Iran, whose output is declining because of Washington’s sanctions, and Venezuela and Libya, whose production has been hampered by political and economic turmoil and civil strife.

So aside from Saudi Arabia, only a few OPEC countries — chiefly Kuwait and the United Arab Emirates — are likely to contribute much to cuts, analysts said.