Evacuation threat by Landlord

We are tenants staying on rent in Mira Road. Now the current owner has sold the property to a new owner and have the registration done a week ago. Now the owner wants us to vacate the flat immediately before 15th April. Our agreement with the previous owner was until July. My rents were paid on or before time for every month to the previous owner. We have seen a flat after so many options for which we will get in hand on 25th April 2019. Is there any way to stop the owner to threaten us and ask a 15 days extension until 30th April 2019. We will be making new flat agreement this Saturday.