Pope Francis appealed for peace and dialogue as the Syrian government and its allies prepare to launch strikes against the last major rebel stronghold in Idlib province in the country's northwest.
They are also home to some 3 million civilians.
However, the London-based watchdog said the rebel attack against the government positions in Latakia was not carried out by drones but through artillery shelling.
Both he and his Syrian counterpart, Walid Muallem, have accused rebels of preparing to stage a chemical attack in Idlib in order to blame pro-government forces and draw new USA military retaliation.
But Turkey, whose army has a string of observation posts around the edge of the rebel area, has warned against such an offensive.
Tuesday's attacks, if confirmed, came just hours after US President Donald Trump warned Syria against launching a reckless attack on the country's last opposition and rebel stronghold with the help of Russian Federation and Iran, saying the offensive could trigger a "human tragedy".
Dorothy's stolen ruby red slippers found after more than a decade
Stein added that officers investigated tips over the years, but many led to reproductions of the slippers, not the real thing. The ruby slippers were swiped during a heist in which someone broke through a window and broke into the small display case.
The Britain-based monitor, which relies on sources in Syria for its reports, said at least nine civilians, including five children from the same family, were killed in the raids, while 10 people were wounded. "Don't let that happen!" he added.
Kremlin spokesman Dmitry Peskov said on Tuesday that Idlib had transformed into a "pocket of terrorism", and that the Syrian government is "getting ready to solve this problem", Syrian state news agency SANA reported.
Seized from government forces in 2015, Idlib and adjacent areas form the last major chunk of territory still in rebel hands.
After seven years of war, the northern province of Idlib has become the rebels' final bastion. Hay'at Tahrir a-Sham (HTS), the largest and most powerful rebel bloc in the province, is spearheaded by a former Al-Qaeda affiliate and has frequently sparred with other opposition groups for control of Idlib.
Mr Zarif said it was necessary to consult "with our Syrian friends" ahead of the September 7 summit, according to Fars.
According to a report by the Syrian Center for Policy Research, the conflict has claimed the lives of over 470,000 people, injured 1.9 million others, and displaced almost half of the country's pre-war population of about 23 million within or beyond its borders.
Asked about Mr Trump's tweet, Mr Peskov said such warnings do not take into account "the unsafe and negative potential" of the rebel-held enclave and show that the White House does not have a "comprehensive approach" to solving the Syria crisis.