You mean you created it as a character animation in the default outfit of the npc character, yes?
In the dialog section, you may have noticed that there's a bit on the right hand side where you can create custom action parts - "execute action". Any action parts you place in there should be executed after the npc speaks their part.
Quick note: if you leave the reponse part & alternate text input boxes empty & enable the alternative text option, then it will skip both the player text & npc text & immediately execute any action parts you added, which allows you to get more creative with dialog based conversations as you can have a conversation with more than 1 npc that way or have some other npc in the scene chip in, or play custom animations, change conditions & so on.