The Tass news agency reported Friday that Russia had "conducted 18 sorties against 12 facilities of the Islamic State terrorist group," quoting Igor Konashenkov, the spokesman for the Russian Defense Ministry.
But international officials and some people inside Syria doubt that Russia is limiting its attacks to ISIS.
Friday marks the third day Russia has carried out airstrikes in Syria.
An international coalition is urging Russia to immediately cease attacks on the Syrian opposition and civilians and focus instead on fighting the ISIS
The joint statement adds new emphasis to global concern about Russia's true aims in Syria -- and whether it is concerned primarily with attacking ISIS or with propping up Syrian President Bashar al-Assad
and protecting its military base in Syria.
"We express our deep concern with regard to the Russian military build-up in Syria and especially the attacks by the Russian Air Force on Hama, Homs and Idlib since yesterday which led to civilian casualties and did not target Da'esh," said the statement, jointly issued late Thursday by the United States, the United Kingdom, Turkey, France, Germany, Qatar and Saudi Arabia.
Da'esh is another name for ISIS.
"These military actions constitute a further escalation and will only fuel more extremism and radicalization," said the statement, which was on the website of the Turkish Foreign Ministry.
Russia said Friday that it did not carry out any strikes against civilians in Syria.
"I would like to stress that there were no strikes against civilian infrastructure, especially against buildings where there could have been or were peaceful residents," Igor Konashenkov, the Defense Ministry spokesman, told reporters in Moscow.
'We have been receiving military support from America'
Russian warplanes carried out two airstrikes Thursday targeting the training camp in Idlib of a Syrian rebel group supported by the CIA, a rebel commander told CNN.
"Our training camp is located in Jabel al Zawia in Idlib, and we have been receiving military support from America to help fight Daesh in Aleppo and Idlib," said Hassna Haj Ali, the commander of the northern division of Suqur al Jabal brigade.
The group has been fighting ISIS in northern Syria for over a year.
Ali said no one was killed by the Russian airstrikes.
However, Syrian activist Khdaier Khushfa in Homs told CNN via Skype that 17 civilians had been killed in Talbiseh and 11 others in Zafaraniya by the Russian airstrikes Wednesday, and 46 people had been critically wounded.
"We are very concerned of what will happen next. Civilians I spoke to are very scared," Khushfa said. "It's like after five years since the revolution started, we are back to ground zero."
Israel and Russian defense officials set to meet
Senior defense officials from Israel and Russia are scheduled to meet Tuesday in Tel Aviv to address the coordination between the two militaries in the region, the Israel Defense Forces said Thursday.
Next week's meetings will be part of a two-day visit by a Russian military delegation, according to the IDF.