Al Jazeera said Syrian Kurdish YPG units had closed the main route used to supply Raqqa, the de facto capital of the so-called Islamic State (IS) group, from Turkey and were about 30 miles from the north of the city.
The UK-based Syrian Observatory for Human Rights is reporting that IS has had to resort to installing CCTV cameras around Raqqa as it no longer has the manpower to mount security patrols.
The US-led coalition said it had conducted 14 air strikes against IS positions in Syria and nine in Iraq on Friday.
The strikes in Syria included six around Hasaka, the northern city where militants briefly seized a residential area before being pushed back by the Syrian army.
Hasaka is divided into zones run separately by the YPG and the Syrian government.
There were four other strikes near Aleppo, three near Kobani and one near Tal Abyad, destroying fighting positions, vehicles, tactical units and staging areas belonging to the militants, the Combined Joint Task Force said in a statement.
In Iraq there were strikes against the militants near Falluja, Makhmur, Mosul and Sinjar, it said.
Meanwhile, the Syrian army and Shia Hezbollah militia fighters claim to have launched a major assault on the rebel-held city of Zabadani, west of Damascus.
The city, currently held by Sunni militants including the al-Qaeda-linked Nusra front, is one of the rebels’ last strongholds along the Lebanese border and capturing it would be a major strategic gain for forces loyal to president Bashar al-Assad.