Trump said that Syria, Russia and to a lesser extent, Iran, are bombing the hell out of Idlib Province in Syria.
Taking to Twitter, the POTUS wrote: “Hearing word that Russia, Syria and, to a lesser extent, Iran, are bombing the hell out of Idlib Province in Syria, and indiscriminately killing many innocent civilians. The World is watching this butchery. What is the purpose, what will it get you? STOP!"
He tweeted the message shortly before he was to depart for a state visit to Britain.
Idlib is Syria's last jihadist stronghold. Syrian NGOs on Friday decried the international action in the face of mourning violence.
As per the Syrian Observatory for Human Rights almost 950 people had been killed in the latest clashes in Idlib.
Apart from killing dozens of people, the recent bombardments by Syrian and Russian forces in northwest Syria have pushed 300,000 people towards Turkey's border.
In September, last year Russian President Putin and Turkish leader Erdogan brokered a cease-fire for Idlib in the Russian resort of Sochi, preventing a bloody onslaught, despite the fact that Russia has firmly backed Assad and Turkey supports opposition forces. However, nine months later, the truce has failed.
The jihadists have refused to leave the area and the Syrian and Russian forces allied to Syria's President Bashar al-Assad have ramped up air strikes and rocket fire.