"It is an aggressive US provocation, aimed at escalating the situation and triggering conflict," the diplomat told TASS.
As the Cuban Interior Ministry reported earlier, a speedboat registered in the US state of Florida entered the island's territorial waters.
People on board opened fire at a Cuban patrol boat, who fired back. According to the ministry, four people were killed and six wounded among those aboard the US vessel.
The commander of the Cuban border patrol was also injured.