Got threat call to obstruct and create nuisance during social event

I will narrate down the whole event that happened briefly. My sister is getting married next month. After distribution of the wedding cards, i got a call from one of my family member in which he threatened me that he will destroy and create nuisance in all our wedding functions as that particular person has personal disagreements with us. He also threatened us to go to any limit to make this function horrible due to which our image in the society gets shattered. I don't have any call recording of all this as this call was unexpected. Now i want to take legal action against them, as in police protection or a silent warning to those people, so as my wedding and social events go on peacefully. I am v much worried and need help in this matter. Hope you guys can help.