Since Friday evening, clashes in several villages around the city of Manbij have left 101 dead, including 85 members of pro-Turkish groups and 16 from the Kurdish-dominated Syrian Democratic Forces (SDF), the Britain-based Syrian Observatory for Human Rights said.
The SDF said it had repelled "all the attacks from Turkey's mercenaries supported by Turkish drones and aviation".
The Turkish defence ministry said it had "neutralised" 32 Kurdish fighters in northern Syria, without providing further details.
Turkish-backed factions in northern Syria resumed their fight with the SDF at the same time as Islamist-led rebels were launching an offensive on November 27 that overthrew Syrian president Bashar al-Assad just 11 days later.
The pro-Ankara groups succeeded in capturing Kurdish-held Manbij and Tal Rifaat in northern Aleppo province, despite US-led efforts to establish a truce in the Manbij area.
The fighting has continued since, with mounting casualties.
During a visit to Damascus on Friday, German Foreign Minister Annalena Baerbock said security of the Kurds is "essential for a peaceful Syria." She said this requires "an end to the fighting in the north and the integration of the Kurdish forces... in the Syrian security architecture."
The SDF controls vast areas of Syria's northeast, and parts of Deir Ezzor province in the east, where the Kurds created a semi-autonomous administration following the withdrawal of government forces during the civil war that began in 2011.
The group, which receives US backing, took control of additional territory after capturing it from the jihadists of the Islamic State group.
Ankara accuses the main component of the SDF, the People's Protection Units (YPG), of affiliation with the Kurdistan Workers Party (PKK), which has fought a decades-long insurgency in southeastern Turkey and is banned as a terrorist organisation by the government.
The Turkish military regularly launches strikes against Kurdish fighters in Syria and neighbouring Iraq, accusing them of being PKK-linked.
Ahmed al-Sharaa, Syria's new leader and the head of the Islamist group Hayat Tahrir al-Sham (HTS), told Al Arabiya TV in late December that local Kurdish-led forces should be integrated into the national army.
HTS led the coalition of rebel groups that overthrew Assad last month.
