Even though the United States had just had its own revolution to overturn a colonial power it did not support the revolution in Haiti because

Well, for one, Haiti really didn't have anything to offer the United States. No territory. Nothing to trade. Nothing really. But also, the idea of Africans rising up against an oppressive white government and overthrowing them made the United States very nervous, especially since we, at the time, had institutionalized slavery and a culture that was very much steeped in racism. Basically, we were afraid that if we supported the revolution in Haiti, it would encourage our own slaves to revolt against Southern slaveholders.