Erdogan, along with Russia's Vladimir Putin, France's Emmanuel Macron and German Chancellor Angela Merkel met to try and find a lasting solution to the Syrian conflict, in which more than 360,000 people have been killed since 2011. "He is not in a respected position for us", Erdogan said.
Recall that at the summit on Syria in Istanbul, the leaders of Germany, Russia, Turkey and France said that to resolve the situation in Syria is through diplomacy.
The leaders of the four countries urged global community and the parties involved to find a "political solution" to end a conflict that has lasted for more than seven years and killed up to half a million people.
"The quadripartite summit should not be expected to produce any concrete results", Cahit Armagan Dilek, head of the Ankara-based think tank 21st Century Turkey Institute, told Xinhua.
They include divided opinions about Syrian President Bashar Assad, who is backed by Russian Federation and Iran.
"We proposed to our partners that Russia's initiative to convene an global conference on Syrian refugees be supported".
Boost humanitarian aid - The leaders agreed to provide "swift, safe and unhindered" flow of humanitarian aid to the Syrian people.
Kremlin spokesman Dmitry Peskov said on Monday that it was not realistic to expect agreements to be concluded regarding Syria's future at the Istanbul summit.
Since 2015, the European Union has been struggling to cope with an influx of refugees, many from Iraq and Syria, and European countries hope war-torn areas can stabilize so that people can return.More news: Mattis condemns Khashoggi killing, calls it security concern
"It needs to be formed in order to prepare transparent elections monitored by the worldwide community", the French leader noted. He stressed the need to ensure the security of refugees wishing to return to their homeland.
The French president, meanwhile, said that the worldwide community would be watching to make sure that ceasefire agreed in Idlib will be long lasting.
Paris also said it wants the effective launch of an inclusive political process in accordance with a United Nations resolution.
A rival United Nations plan for a committee to write the constitution ran aground this week, with UN special envoy Staffan de Mistura, who attended the summit, saying Damascus rejected the UN having a role in the selection process.
Erdogan's closed-door meetings with Angela Merkel, Vladimir Putin and Emmanuel Macron took place at the Vahdettin Pavilion in Istanbul's Uskudar district.
It accused Turkey of provoking trouble in Syria and supporting jihadist groups, particularly in Afrin and Idlib.
A historical agreement on Syria has been reached, but it's implementation is questionable since the US, UK and Saudi Arabia refused to participate.
Erdogan noted that the leaders called for the completion of the constitution committee's process in Syria as soon as possible.
These reinforcements, according to information obtained by the Anadolu Agency correspondent, aim to strengthen the capabilities of the military units stationed at the border.