President Vladimir Putin has defended Russia's military operations in Syria, saying the aim is to "stabilise the legitimate authority" of Syrian President Bashar al-Assad.
Russia wants to "create conditions for a political compromise" in Syria, he told Russian state TV.
On Monday the EU's foreign affairs chief, Federica Mogherini, called Russia's role "a game-changer". She said: "It has some very worrying elements."
EU ministers are discussing Syria now.
Going into the Luxembourg meeting, several foreign ministers stressed that air strikes should only target so-called Islamic State (IS) fighters and other Islamist "terrorists".
The US and UK governments have accused Russia of attacking mainly "moderate" anti-Assad groups, rather than the jihadists.
Mr Putin denied that that was the case.
"The interventions against Daesh (IS) have to be clearly against Daesh and other terrorist groups, as defined by the UN," Ms Mogherini stressed.
Luxembourg Foreign Minister Jean Asselborn also said "the target is IS and nothing else".
Ms Mogherini said she was especially worried about recent violations of Turkish airspace by Russian jets.
Syrian forces are said to have made significant advances against rebels.
Government gains in Idlib, Hama and Latakia provinces were on Sunday reported both by the Syrian government and opposition activists.
The main battlefront is currently close to the key highway that links the capital with other major cities, including Aleppo. Mr Assad's forces are believed to be seeking to cut off rebels in Idlib.
Speaking to Rossiya One TV on Sunday, Mr Putin said that without Moscow's support for President Assad, there was a danger that "terrorist groups" could overrun Syria.
Mr Assad's government was currently "under siege", he said, adding that militants were "at the edge of Damascus".
He also urged other nations to "unite efforts against this evil (terrorism)".
The US-led coalition - which has been carrying out its own air strikes in Syria - earlier said it would not be co-operating with Russia.
Several countries - including the UK and Turkey - have described Russia's support for President Assad as a "mistake".
Russia said on Sunday its aircraft had carried out more than 60 missions over Syria in the past 24 hours, and that IS was its main target. The attacks began on 30 September.
When asked whether the EU would have a dialogue with Mr Assad, Ms Mogherini stressed EU support for UN efforts to mediate, but did not rule out including Mr Assad in transitional talks.
"We say we have to have all the relevant actors round the table," she said.