"France has always said that Raqqa was a major objective," Defense Minister Jean-Yves Le Drian said on French TV outlet CNews.
"Today, one can say that Raqqa is encircled, that the battle for Raqqa will start in the coming days. It will be a very hard battle, but a battle that is going to be of utmost importance."
The northern city was the first major city captured by ISIS, with its forces in full control by early 2014. Raqqa is the extremist group's operational command headquarters.
It is now largely surrounded, its main supply routes cut off by advancing forces.
US-backed Kurdish and Arab forces are squeezing ISIS from the north, while Syrian government troops -- backed up by Russia -- have been pushing from the west.
The US-led coalition against ISIS has also been carrying out airstrikes against the city. France is one of the 68 partners in the global coalition
to combat ISIS.
Coalition-backed fighters vs. ISIS
The Syrian Observatory for Human Rights, a UK-based monitoring group, said fighting flared on Friday between ISIS militants and fighters from the Syrian Democratic Forces, backed by coalition warplanes.
Clashes occurred in the town of al Karam, about 18 kilometers, or 11 miles, east of Raqqa. The SDF is an alliance of the main Kurdish groups in northern Syria, with the main force made up of People's Protection Units known as the YPG. Several Arab groups and tribes also are part of the coalition.
The coalition-backed fighters are attempting to close in on the city as part of third stage of "Wrath of the Euphrates" military operation. That initiative was launched in November to isolate the city from the countryside.
The observatory said coalition warplanes backed the Syrian Democratic Forces fighting ISIS on the northern bank of the Euphrates River.
The coalition-backed fighters, which carried out heavy shelling with aerial cover provided by warplanes, made advances, the observatory said. Warplanes also carried out several airstrikes on the town of Tabqa. Damage was reported, but there was no word on casualties.
Earlier this week, an airstrike hit a school in al-Mansoura, a town west of Raqqa.
Activists and state-run media said Wednesday that dozens of people
were killed in the strike. Refugees who fled fighting in Palmyra took shelter at the school.
The state-run Syrian Arab News Agency, the activist group Raqqa Is Being Slaughtered Silently and the Syrian Observatory for Human Rights blamed the coalition against ISIS for the airstrike.
But the coalition said it had "no indication that an airstrike struck civilians near Raqqa." It said, "We will provide this information to our civilian casualty team for further investigation."
A message on Twitter from the ISIS-affiliated news agency Amaq claimed the suspect in the terror attack in London on Wednesday was a "soldier" of the terror group and inspired by its message.
The outlet provided no evidence of direct links between the suspect, 52-year-old British man Khalid Masood, and the terror group.
In his interview, Le Drian also praised London for its resilience in the face of the Westminster terror attack.
He said that he would be going to London later Friday to meet Britain's Defense Secretary Michael Fallon, and three French students who were injured in the attack.