Russian President Vladimir Putin said Moscow will fulfil its energy contracts with European powers and scolded the United States for interfering in Russia's relations with Europe.
"We certainly guarantee the fulfilment of our obligations before our European customers in full," Putin said in a Kremlin statement.
"The issue is not about us, the issue is about securing transit through Ukraine."
"I want to say again: We do not intend and do not plan to shut off the gas for Ukraine," he said at a meeting of his Security Council.
Putin has written 18 European leaders warning Moscow may turn off supplies to Kiev if it refuses to pay its outstanding gas debts to Russian energy giant Gazprom.
Putin's spokesman said that the heads of state had yet to respond to the letter, which prompted the US state department to condemn "Russia's use of energy as a tool of coercion."
The Russian President responded to criticism from Washington by criticising American foreign policy.
"It's strange because reading other people's letters is not good. I did not write to them, I wrote to the consumers of gas in Europe," he told the meeting.
"Everyone is used to the fact that our American friends are eavesdropping but peeping is really not nice (too)," he quipped.
Tensions between the US and Russia escalated when Moscow annexed Crimea in a widely disputed referendum. In return, Washington and Brussels imposed asset freezes and travel bans on a number of individuals with close ties to the Kremlin.
Although the threat of a military conflict appears increasingly remote, Russia has upped the economic pressure on Ukraine by threatening to cut off gas supplies if Kiev does not settle $2.2bn (£1.3bn, €1.6bn) in outstanding gas bills immediately and accept a new price for gas.
Ukraine's interim government has refused to pay the inflated price, calling it an act of "economic aggression," and has not indicated when it plans to clear the outstanding bills.