State-owned Gazprom said supplies via the Nord Stream 1 pipeline would go down to a daily maximum of 67 million cubic metres, down from 167 million cubic metres earlier in the week, citing necessary repairs.
The cuts represent an approximately 60 per cent reduction in gas supplies to Germany through the pipeline within just two days.
It comes as European countries try to wean themselves off their dependence on Russian fossil fuels in light of the war in Ukraine, with limited success.
German Economy Minister Robert Habeck said in a video posted on Twitter that "now is the time" to save on energy usage.
"Every kilowatt hour helps in this situation," he said.
Although supplies to Germany were secure with the contribution of other, albeit more expensive, sources, "We must be vigilant," he said.
"Above all we must not let ourselves be divided, as this is what (Russia President Vladimir) Putin intends."
The Nord Stream 1 pipeline is Germany's main source for the delivery of Russian gas.
Siemens Energy announced on Tuesday that one of the Nord Stream 1 gas turbines that had recently undergone repairs in Canada could not currently be shipped back from Montreal due to sanctions on Russia.
Habeck said however he suspected the real reason for the reduction in gas flows by Gazprom was political.
Gazprom chief Alexey Miller said on Thursday he saw no quick solution to the problem.
"The turbine is in the factory, Siemens can't pick it up and other turbines don't fit," Miller said at an economic forum in St Petersburg.
He suggested that the new Nord Stream 2 pipeline - a project which Germany put on ice after the outbreak of the war in late February - could theoretically be put into use.
Russia has cut off the flow of gas to several European countries in recent weeks amid disputes over sanctions imposed on it for its invasion of Ukraine and subsequent European refusals to pay for gas in roubles, something Russia has demanded in an attempt to prop up its currency.
Energy prices have risen significantly due to the decrease in gas flow from Russia to Europe, with many energy analysts fearing Russia is set to turn off the taps to Europe altogether as a pressure tactic.
European Union Economy Commissioner Paolo Gentiloni warned on Thursday that the continent's economy could enter recession if Russian gas supplies stop.
