President Jacques Chirac has warned France that no country is safe from terrorism, amid tight security during the traditional Bastille Day events.
Bastille Day pomp - but Mr Chirac's ratings have plunged
"The terrorists have a different mentality," he said in a TV interview, a week after the London bombings.
"No country in the world is safe from attacks," he warned.
Mr Chirac stood in an open jeep at the Champs Elysees parade commemorating the storming of the Bastille prison in 1789 - the start of the French revolution.
State of alert
About 5,000 police were deployed for this year's celebrations in Paris, which featured a military contingent from Brazil.
Protecting the event has been a priority since a gunman tried to kill Mr Chirac during the 2002 parade.
Defence Minister Michele Alliot-Marie said France must maintain "a maximum level of vigilance".
Among the enhanced security measures, spectators had to pass through metal detectors, while police filmed the crowds and limited access to underground stations.
Pierre Mure of the Paris police department said sharpshooters were also deployed on rooftops.
The BBC's Jacky Rowland in Paris says the festivities coincide with a period of self-doubt in France, following several disappointments which many French people blame on Mr Chirac.
Losing the 2012 Olympic bid was a particularly bitter blow to Paris.
In the French television interview, Mr Chirac defended the country's social model of welfare for its citizens, saying France had far fewer children below the poverty line than Britain.
And he said that although Britain had lower unemployment, France was investing more in research and education, putting it in a better position for the future.
Our correspondent says the next presidential elections are still almost two years away, but it is already beginning to feel like the end of the Chirac era.
An opinion poll carried out for Le Parisien newspaper suggests that six out of 10 French people no longer have confidence in their president.
At home, Mr Chirac looks out of touch, while internationally he looks isolated, our correspondent reports.
Brazilian President Luiz Inacio Lula da Silva attended the ceremony alongside Mr Chirac.
Two battalions from the Brazilian army were the guest stars of the parade and Brazilian jets also participated in the traditional military fly-past.