Well, say for example you're using the animation "Attack", in which, you have events prepared for damaging, such as;
On Collisions Player + Enemy
+Is "Attack" animation playing
+Is Frame 5 playing
Then making "Cancelling" would be a breeze! Simply detect the jump ("Has Space key been pressed?", "On Jump" in platform behaviour), set animation to "Jump", thus cancelling the rest of the Attack animation!