Syrians gather to protest against a proposal from the Turkish foreign minister for reconciliation between the Syrian government and the opposition, in the border town of Azaz in the rebel-held north of the Aleppo province, on August 12, 2022. AFP
Turkey has fervently opposed Syrian President Bashar al-Assad, backing rebels calling for his removal and opening its doors to refugees.
Cavusoglu's comments were seen as an apparent easing of Ankara's long-standing hostility towards Assad's government and enraged the Syrian opposition and rebel groups.
Syrians took to the streets after Friday prayers in major northern cities including Azaz, Al-Bab and Afrin, which are under the control of Turkish forces and their Syrian supporters near the Turkish border.
"As revolutionaries, we are united here to reject any reconciliation with the regime, as that means destruction and displacement of millions of Syrians," said Yassin al-Ahmad, a displaced Syrian residing in Al-Bab.
"This reconciliation is not in our hands, and it is not in Turkey's hands. For us it is suicide and a crime," the 37-year-old added.
Protesters brandished Syrian opposition flags, and one banner read: "No reconciliation, the revolution continues."
'Blood of martyrs'
Cavusoglu had told diplomats on Thursday: "We have to somehow get the opposition and the regime to reconcile in Syria. Otherwise, there will be no lasting peace, we always say this."
Protesters also demonstrated in Idlib province, controlled by Hayat Tahrir al-Sham, the former Syrian branch of Al-Qaeda, and other rebel groups.
Dozens gathered at a Turkish army checkpoint in Idlib's Mastuma area, shouting: "Down with the (Syrian) regime," and denouncing the Turkish minister's statements.
"We are against reconciliation. We will not forget the blood of the martyrs, the pain of the detained, and the massacres," said protester Sanaa al-Ali.
The Britain-based Syrian Observatory for Human Rights, a war monitor, said protests were held in more than 30 locations in the country's north and northwest.
Small protests had already begun overnight in some areas, including Al-Bab, where dozens gathered, chanting against Turkey.
Some demonstrators burned a Turkish flag, while others took down Turkey's colours hung up around the city, an AFP photographer reported.
Dozens of others gathered at the Bab al-Salama crossing to Turkey, many shouting: "Death rather than indignity."
In a statement Friday, Turkish foreign ministry spokesman Tanju Bilgic said: "Turkey played a leading role in maintaining the ceasefire on the ground" and in talks on drawing up a new constitution, although they have made no progress.
Ankara "threw full support behind the opposition and the negotiation committee throughout the political process", he said.
"Currently this process is not moving forward because the regime is dragging its feet. The issues expressed by our minister yesterday also point to this," he said.
Turkey's top diplomat revealed on Thursday that he had held a short meeting in Belgrade in October with his Syrian counterpart Faisal al-Meqdad, adding that communication had resumed between the two countries' intelligence agencies.
But he denied direct talks between Turkish President Recep Tayyip Erdogan and his Syrian counterpart Bashar al-Assad, despite long-standing calls from Russia for such dialogue.
Cavusoglu added that Turkey would continue its fight against "terrorism" in Syria, following warnings from Ankara since May that it could launch new strikes on Kurdish-held areas in north and northeast Syria.
Ankara has launched successive military offensives in Syria. Most have targeted Kurdish militants that Turkey links to a group waging a decades-long insurgency against it.
Cavusoglu's comments have sparked widespread anger among the opposition.
Renowned figure George Sabra wrote on Facebook: "If Cavusoglu is concerned with reconciling with the Syrian regime, that is his business. As for the Syrians, they have a different cause for which they have paid and continue to pay the dearest price."
The war has killed about half a million people and displaced millions more since starting in 2011 with the brutal repression of anti-government protests.