The German government on Sunday said it had "noted with regret" US plans to expand sanctions on the Nord Stream 2 gas pipeline between Russia and Germany.
"New sanctions would constitute a serious interference in European energy security and EU sovereignty," a statement by the Foreign Ministry said.
On Thursday, US senators approved Nord Stream 2 sanctions, saying the pipeline will increase Russia's economic and political influence in Germany and other European countries.
The Protecting Europe's Energy Security Clarification Act follows legislation signed by President Donald Trump last year, which prompted Swiss-Dutch company Allseas to stop undersea work, delaying the project.
Led by state-run Gazprom, two Russia-owned pipe-laying vessels may now finish the remaining 100 miles (160 kilometers) of the project.
Russian President Vladimir Putin said the pipeline could be completed by late 2020 or early next year.
Republican Senator Ted Cruz, who spearheaded the new legislation, said it "makes clear those involved with vessels installing the pipeline will face crippling and immediate sanctions."
Jeanne Shaheen, a Democatic senator, said the Nord Stream 2 pipeline threatens Ukraine and Europe's energy independence and "gives Russia an opening to exploit our allies."
Moscow claims that Washington wants to scuttle the pipeline project to ensure that US natural gas providers could sell exports to the EU market at a higher price.
The Trump administration has touted exports of US liquefied natural gas (LNG) as an alternative to Russian supplies, calling it "freedom gas."
The Nord Stream 2 project is backed by many politicians and energy companies in Germany, as Europe's biggest economy seeks to end the use of coal and nuclear power.
Last week, German Economy Minister Peter Altmaier slammed Washington for "escalating this sanctions threat, which is extraterritorial and thus in conflict with international law."
Jens Mueller, Nord Stream 2 spokesperson, warned that European households and industries will pay "billions more" for gas if the pipeline is not built.
"Decisions about European Union energy policy should be left to Europeans," Mueller said.
shs/ (Reuters, dpa)