This is common with toddlers. They don’t understand that they need to wait until their elders finish the conversation. They will start talking immediately when something struck them and they like to have your attention.

You need to develop their habit slowly by explaining them that this is interruption. Guide them to use “please” or “may” before they interrupt and that you sometimes can attend them cutting your conversation and other times they need to wait for you to finish the ongoing conversation.

It may not work for the entire toddler doom but they would eventually learn this and would become well-mannered in years to come. Please don’t use force or punishment. It wouldn’t work rather would cause more damage.