He spoke during a meeting with foreign ambassadors late Wednesday, according to the state-run Turkish Anadolu Agency.
"What happened was destruction all over, burning, something you can't describe", said Ali al-Mheymid, 50, who escaped the village of Sarjah in Idlib province with his family last week.
During the first 12 days of September, "available information indicates that a sharp increase in hostilities and fears of further escalation has led to the displacement of over 38,500 people", the United Nations humanitarian agency (OCHA) said. The UN has described it as a "dumping ground" for people evacuated and displaced from elsewhere in Syria during the seven-year war.
"We share these coordinates so there is no doubt that a hospital is a hospital", Panos Moumtzis, U.N. regional humanitarian coordinator for the Syria crisis, told a briefing.
"We had come (to Idlib) without anything", he said. They later went to southern Syria, only to move again in a withdrawal deal when government forces defeated rebels there around two months ago.
Syrian activists meanwhile said new military reinforcements had arrived to beef up Turkish observation points inside Idlib.
The Turkish military does not comment on troop movements, but Reuters television footage has shown military convoys heading to the border region in the last week.
UN Special Envoy for Syria Staffan de Mistura at a meeting in Geneva
Turkey deployed hundreds of its soldiers to 12 observation posts that ring Idlib, following a de-escalation agreement reached with Russian Federation and Iran a year ago to freeze the lines of the conflict, effectively placing Ankara as a protector of the province.
Russian Federation and Iran are major allies of the Syrian government, while Ankara backs some rebel fighters.
Rebels also said some pro-Assad forces had left frontlines in northwest Syria in recent days.
But the bombing has let up in the last 24 hours.
Turkey, already hosting 3.5 million Syrians, says it can not take in another wave of refugees. It is seeking to gain time to support its efforts, it said, to separate radical militants from moderate opposition groups it backs. We will continue our efforts in global platforms as well.
He said the postponement of the military operation against the rebels in Idlib relies on "to what extent the global community members could assist in the separation of moderate opposition from radicals in Idlib".
Eric Pahon, a Pentagon spokesman, said the US and its allies are concerned about the deadly consequences of such an offensive. Parties to this conflict have clear and unambiguous obligations to spare the civilian population from the scourge of war, and the presence of designated terrorists or legitimate military targets does nothing to diminish such obligations.