President Francois Hollande said there was "at this stage" no apparent link between a knife attack on Saturday on a soldier in Paris and the murder of a soldier in London this week.
The comment came after a man armed with a box cutter attacked a French soldier patrolling the business district of Paris and stabbed him in the neck.
Police sources said the victim would survive the attack but gave no information on possible motivation for the assault.
The soldier was in uniform and armed and was patrolling as part of France's Vigipirate anti-terrorist surveillance scheme in La Defense, which at weekends is packed with shoppers.
The attacker managed to flee after the assault.
Hollande, speaking during a trip to Ethiopia, said there was no immediate sign that the incident was linked to the deadly attack on the British soldier in London.
"I do not think that at this stage a link can be made," he told reporters accompanying him in Addis Ababa as he attended the 50th anniversary of the creation of the African Union.
Hollande said all possibilities must be examined and that nothing was so far known about the identity of the attacker.
On Wednesday, a soldier was hacked to death in London a brazen attack in broad daylight by two men wielding knives and a cleaver who later launched into a tirade against the British government and its military involvement in Muslim countries.
France's defence and interior ministers in a joint statement condemned the Paris attack.
Armed and uniformed soldiers patrol a number of prominent tourist, business and transport sites in London, such as the area around the Eiffel Tower and the city's major train stations.
Hollande earlier this month said France was taking seriously a call by Al-Qaeda's north African wing for Muslims worldwide to launch attacks against the country's interests over its military operation in Mali, where French soldiers this year intervened to fight Islamist extremists.