France's President Emmanuel Macron. AFP
Sandu was sworn in for a second term in December, after Russia was accused of interfering in elections in the former Soviet republic that borders Ukraine.
"We have decided to again reinforce our cooperation to increase Moldova's resilience faced with foreign interference," Macron said as both signed a deal to cooperate on detecting digital disinformation.
Sandu said both countries were "committing to join forces in fighting disinformation... Because in today's world, truth is as vital as security".
Sandu accused Russia, which launched its invasion of neighbouring Ukraine three years ago, of using the "tools of a modern imperialist".
Macron's office said Viginum, the French government agency set up to detect digital disinformation campaigns, would increase its work with the Moldovan Strategic Communication Centre, including to "protect electoral processes".
Sandu, the country's first woman elected head of state, owed her re-election in large part to a strong turnout from Moldova's large diaspora.
But rural areas of the country -- sandwiched between NATO member Romania and war-torn Ukraine -- and separatist Transnistria, where Russian troops are stationed, remain pro-Moscow, as does the autonomous Gagauzia region.
Authorities reported numerous "attempts at destabilising" the election, including disinformation, vote buying, death threats, cyberattacks and bussing in voters.
The Kremlin accused Moldova of suppressing "the opposition and independent media, especially Russian-language outlets".
Short link: