The blockade established by the US around Cuba to stop the Soviet Union from having any goods, materials, or weapons enter Cuba was supposed to help Kennedy in his goal to get the missiles out of Cuba. The reason why is because this blockade would result in the Soviet Union from getting any more missiles in.
Once this blockade was in place, the Soviet Union would have to communicate with the US in order to discuss the situation at hand. Kennedy hoped that this would result in a deal that would result in the missiles being removed from Cuba.
