"There is a threat to Prime Minister's life from terrorists, mafias and political mafias. Support him on demonitisation move and pray for his safety," Ramdev said in a tweet.
Ramdev, who has since 2010 been pitching for discontinuation of Rs 500 and Rs 1000 currency notes, had earlier said the "historic" decision will help recover Rs 10 lakh crore black money from within the country itself.
Ramdev had claimed he had made a proposal for demonetisation of these currencies to former Prime Minister Manmohan Singh, who despite seeing logic in it had "politely" turned it down.
"Modiji did the job step by step. He first opened accounts of crores of people. He gave chance to those with black money to deposit their money. And third thing, he did this financial surgical strike which is historic."
"Now, this will benefit employees of seths (rich). The servants too will have Rs 5 to Rs 10 lakh in their accounts. Because those with black money will give the money to their servants to be deposited in the latter's account. These servants will thank Modi," he had said.
(With PTI inputs)