The warning came as Syrian government forces captured a hill on the edge of the northern city of Aleppo under the cover of air strikes.
intervention against the Syrian army "will lead to terrible, tectonic consequences not only on the territory of this country but also in the region on the whole".
She said regime change in Syria would create a vacuum that would be "quickly filled" by "terrorists of all stripes".
US-Russian tensions over Syria have escalated since the breakdown of a ceasefire last month, with each side blaming the other for its failure.
Syrian government forces backed by Russian warplanes have launched a major onslaught on rebel-held parts of the northern city of Aleppo.
Syrian troops pushed ahead in their offensive in Aleppo on Saturday, capturing the strategic Um al-Shuqeef hill near the Palestinian refugee camp of Handarat which government forces captured from rebels earlier this week, according to state TV. The hill is on the northern edge of the Aleppo, Syria's largest city and former commercial centre.
The powerful ultraconservative Ahrar al-Sham militant group said rebels regained control of several positions they lost in Aleppo in the Bustan al-Basha region.
State media said 13 people were wounded when rebels shelled the central government-held area of Midan.
Air strikes on Aleppo struck a clinic in the eastern rebel-held area of Sakhour, putting it out of service, according to the UK-based Syrian Observatory for Human Rights and the Local Coordination Committees. They said one person was killed in the air strike.
Opposition activists have blamed Syrian president Bashar Assad's forces and Russia for air strikes which hit civil defence units and clinics in the city where eastern rebel-held areas are besieged by government forces and pro-government militiamen.
On Friday, the international medical humanitarian organisation Doctors Without Borders demanded that the Syrian government and its allies "halt the indiscriminate bombing that has killed and wounded hundreds of civilians — many of them children," over the past week in Aleppo.
"Bombs are raining from Syria-led coalition planes and the whole of east Aleppo has become a giant kill box," said Xisco Villalonga, director of operations for the group.
"The Syrian government must stop the indiscriminate bombing, and Russia as an indispensable political and military ally of Syria has the responsibility to exert the pressure to stop this."
It said from September 21 to 26, hospitals still functioning in Aleppo reported receiving more than 822 wounded, including at least 221 children, and more than 278 dead bodies -including 96 children — according to the directorate of health in east Aleppo.
Sweden's foreign minister Margot Wallstrom criticised attacks on civilian targets writing on her Twitter account: "Unacceptable to bomb civilians, children and hospitals in #Aleppo. No humanity. Assad & Russia moving further away from peace."
In the eastern province of Deir el-Zour, warplanes of the US-led coalition destroyed several bridges on the Euphrates river, according to Syrian state news agency SANA and Deir el-Zour 24, an activist media collective. The province is a stronghold of the Islamic State group.
SANA said that among the bridges destroyed was the Tarif Bridge that links the eastern city of Deir el-Zour with the northern Syrian city of Raqqa, the extremists' de-facto capital.