Trump, who will take over as U.S. president in January, has said he wants a "good relationship" with Russia and President Vladimir Putin, alarming some in the EU who fear a policy shift that softens the U.S. stance on the Ukraine crisis, Reuters wrote.
The sanctions were first imposed shortly after Russia annexed the Crimea peninsula from Ukraine in 2014 and rolled over for six-month periods since then.
Five European diplomats told Reuters they expected EU leaders to extend the main economic sanctions in Brussels next month – before Trump takes office. The decision requires unanimity among the 28 member states and the economic sanctions are now in place until the late January, 2017.
"The roll-over in December should still happen. There is no change on the ground in Ukraine ... there is really no argument not to extend them," said a European diplomat.
"But then, after Trump's inauguration, who knows where he takes us. It may become way more difficult."
Under President Barack Obama, the United States has also imposed sanctions on Russia and has urged the bloc to remain united over them.
But the measures' effectiveness has been increasingly questioned by EU member states Italy, Hungary, Greece and Cyprus, all of which have close business ties with Moscow.
Read alsoPutin's not going into Ukraine (if I'm President): Trump's key quotes on UkraineDuring his election campaign, Trump adopted a more open-minded stance on Putin than current U.S. officials who consider him an autocrat bent on suppressing dissent at home while bullying his neighbors and projecting Russia's power abroad.
Trump has not said what he would do to revive ties with Russia. EU diplomats fear a softening of the U.S. position would be seized on by the Kremlin in the hope of weakening the bloc's own resolve on sanctions.
"After Trump is inaugurated in January, if there really is a rapprochement with Putin, it would deepen divisions within the EU on Russia and would make keeping sanctions in place more difficult," a diplomat in Brussels said.
Another envoy said: "The EU must make its own decision in December but the complication comes if in January the United States signals that it is going to change its policy. That could affect EU unity."