The president announced the move in December, prompting concerns that Syrian Kurds, who had helped the USA fight Islamic State, would be left at the mercy of neighbouring Turkey, which views some of them as terrorists.
Senior US officials were shocked too, among them Defense Secretary Jim Mattis, who quit in protest.
Turkey on Saturday welcomed the latest statement made by Washington's top diplomat over Ankara's right to defend itself from "terrorists" after the US withdraws from Syria. "The bulk of recent attacks show how we are more committed than ever to act against Iran in Syria, as we promised".
The U.S. decision has injected new uncertainty into the eight-year-old Syrian war and spurred a flurry of contacts over how the security vacuum will be filled in the swathe of northern and eastern Syria where the U.S. forces are now stationed. Using his typical mode of communication to reaffirm the withdrawal of American troops from the ground, the U.S. president warned Ankara against seeing this as an opportunity to stage any military campaign against Syrian Kurds.
Robertson, in his statement, said the coalition had carried out "logistical measures" to support a withdrawal but did not enter into details.
He said: "Terrorists can't be your partners and allies".
IS still holds territory on the western bank of the Euphrates, between areas controlled by the Syrian government and its Russian and Iranian-backed allies.
Several weeks later, national security adviser John Bolton said the withdrawal will have a longer timeline, and will not be undertaken until Kurdish fighters are protected and ISIS is defeated in the war-torn country.
Pompeo's call with Cavusoglu came as the top USA diplomat continues a marathon Middle East tour, which has taken him to Cairo, Bahrain and the United Arab Emirates.
Islamic State militants are "living their final moments" in the last enclave they hold near the Iraqi border, where US-backed Syrian Democratic Forces are attacking them, an SDF official says.
"We hope we can turn the corner here", Mr Pompeo added.
The United States announced in December plans to withdraw some 2,000 troops from Syria.
Pompeo's remarks follow tensions between the United States and Turkey over the fate of Washington's allies in the fight against ISIS.
Pompeo said Friday that Washington recognized "the Turkish people's right and Erdogan's right to defend their country from terrorists". "We also benefit but it is now time to bring our troops back home".
Maria Zakharova, a Russian Foreign Ministry spokeswoman, said it was important for Syrian Kurds and the Syrian government to start talking to each other in light of the U.S. withdrawal plans.
"In this regard, establishing dialogue between the Kurds and Damascus takes on particular significance. After all, the Kurds are an integral part of Syrian society", Zakharova said.
According to the sources, the ministers discussed the latest developments in Syria.