The Haitian Revolution itself was motivated by the desire to end slavery in Haiti and was carried out between 1791 and 1804. The term "genocide" is sometimes used for the massacre of French Creoles after the success of the revolution, when all of Haiti was already under rebel control. Previously, in 1803, rebel leader Jean-Jacques Dessalines had executed hundreds of captured French soldiers but guaranteed the safety of the civilian population.

On 1 January 1804, when Haiti was declared independent, Dessalines gave a speech in Gonaives stating:

It is not enough to expel from our country the barbarians [the French] that drenched it in blood for two hundred years... . We must by one last act of national sovereignty secure for all eternity the reign of liberty in our motherland... .
[Soldiers,] give to all nations a terrible, but just example of the vengeance that must be exacted by a people proud to have found freedom again, and eager to preserve it. Let us frighten all those who would dare to steal our freedom; let us start with the French! May they shudder when they approach our coastline, either because they remember all the exactions they committed, or because of our horrifying pledge to kill every Frenchman who soils the land of freedom with his sacrilegious presence.

Over the next four months, death squads operating under Dessalines' orders roamed around the island and systematically executed white French that were found. The massacre was not restricted to slave-owners; merchants and working-class white French people were also execution. Women and children were killed, although some women were given the choice of marrying a black man or facing death.

A few thousand people died in this massacre. This may not seem like a lot compared to better known genocides like the Holocaust, but in international law genocide does not have a minimum number of victims to qualify. Instead, genocide is defined as killing aimed at the entire or partial destruction of the targeted group. By that standard, the 1804 massacre was a genocide. It was clearly intentional and the bulk of the white French people in Haiti at the time were killed, while very few were left on the island.

The 1804 massacre is sometimes inaccurately labeled a "white genocide" even though whites who weren't French were not harmed.

In all cases of genocide, the perpetrators believe it is justified for some reason and the victims deserve their fate. In most of these cases, the justification is easily rejected. For example, hardly anyone except Holocaust deniers would take seriously the outlandish conspiracy theories put forward in Nazi propaganda to justify the Final Solution. Addressing the question of whether genocide is ever justified, Adam Jones classifies the Haitian massacre as one of those that contain "morally plausible" justification. In April 1804, Dessalines announced, "We answered these cannibals’ war with war, crime with crime, outrage with outrage. Yes, I have saved my country, I have avenged America." Not only was slavery in Haiti an incredibly inhumane and deadly practice, but also both sides had just fought an extremely bloody war that included massacres of rebels by the French army. Dessalines saw eliminating the white population as necessary to building a new Haitian country (another common rationale for committing genocide) but he was also eager to establish friendly relations with countries that allowed slavery.

But if we're asking the question if the massacre (not the revolution) is justified, then surely the consequences must be assessed. Not only did the massacre involve guilt by association—killing people who were not personally responsible for the evils of slavery or war crimes against black Haitians—but it also had negative consequences for Haiti, according to black Marxist historian CLR James. James saw no need to "waste one tear or one drop of ink" on white victims, but also stated that Haiti's "difficulties doubled by this massacre". Another negative consequence of the massacre was hardening attitudes of whites in the Southern US to slavery. Pro-slavery advocates were able to argue that if slavery were ended in the US, Southern whites would face the same fate as French settlers in Haiti.

For the view of this massacre as a genocide see:

Girard, Philippe R. (2005). "Caribbean genocide: racial war in Haiti, 1802–4". Patterns of Prejudice. 39 (2): 138–161.

Girard, Philippe R. (2011) The Slaves Who Defeated Napoleon: Toussaint Louverture and the Haitian War of Independence 1801–1804 University of Alabama Press

Jones, Adam. (2009) "On the Genocidal Aspect of Certain Subaltern Uprisings: a Research Note", in Genocides by the Oppressed: Subaltern Genocide in Theory and Practice. Indiana University Press

As a disclaimer, according to family lore some of my ancestors lived on Haiti after fleeing from the French Revolution and escaped to Philadelphia during the Haitian Revolution. (My mom and aunt disagree whether they owned slaves or were staying on someone else's plantation). In my view, the Haitian Revolution itself was 100% justified to end slavery and gain independence from France, but afterward the rebels should have refrained from committing massacres.