EU ambassadors who met on Tuesday had noted some "encouraging developments" since the 5 September ceasefire was agreed, an EU spokeswoman said.
But other parts of the peace deal "will need to be properly implemented", said the spokeswoman, Maja Kocijancic.
The sanctions target senior Russian officials, as well as Russia's oil industry, defence firms and banks.
Western governments and the Ukrainian authorities in Kiev accuse Russia of supplying the separatist rebels in eastern Ukraine with heavy weapons and soldiers.
Russia denies the allegations.
EU and US sanctions have been in place since Russia's annexation of Crimea in March.
At least 3,200 people have died in fighting since April in Ukraine's Donetsk and Luhansk regions, and thousands of civilians have fled the conflict.
A shaky ceasefire has held since 5 September, and the two sides have since agreed to set up a 30km (19-mile) buffer zone.
But there have been frequent flare-ups of violence.
At least seven Ukrainian soldiers died in a clash with pro-Russian rebels near Donetsk airport on Monday - the deadliest single incident for the military since the truce deal.
A tank shell hit the vehicle carrying the troops, officials said.
More heavy shelling was reported on Tuesday in the Donetsk airport area.
Last week Ukraine's Prime Minister, Arseniy Yatsenyuk, told the UN General Assembly that Russian troops were still operating in eastern Ukraine.
He urged the West not to lift sanctions until his country regained control of all its territory.
Both the US and the EU have said sanctions could be lifted if the situation on the ground improves sufficiently.
The EU is to keep sanctions against Russia in place, judging that Ukraine's peace deal is not fully effective.