Video report by ITV News correspondent Emma Murphy
The French prime minister was greeted by boos and calls to resign as joined thousands to remember the 84 victims of the lorry attack in Nice.
There were angry scenes as Manuel Valls arrived at the Monument du Centenaire ahead of a minute's silence.
As Valls laid a wreath, on the third day of national mourning, crowds booed and shouted "resign".
The government has faced criticism over national security after the country was hit by yet another terrorist attack.
ITV News correspondent Emma Murphy witnessed the angry scenes.
Ex-President Nicolas Sarkozy has accused the government of bad policies which he says failed to prevent three major attacks in the past 18 months.
In the latest attack, Tunisia-born Mohamed Lahouiaej Bouhlel drove a 19-tonne lorry through the crowd celebrating France's national Bastille Day holiday.
A poll conducted four days after the attack in Nice found two-thirds of French people do not trust their government in the fight against terrorism.
Explaining the anger towards Valls, one French woman said people feel a stronger prime minister is needed amid the continued threat from terrorism.
"They want him (Mr Valls) to resign because he didn't put enough police on on the day," said the 60-year-old resident. "I was there (on Thursday) and didn't see police.
"It's terrible to say but we need a stronger prime minister with laws against radicalism.
"I am very sad. It (the attack) has broken families apart for nothing."