Based on the information you provided with your question, I am wondering if the current owner is wanting you to pay them the rental payments.
Give us more information, which might enable us to provide you with more specifics.
How did the previous owner contact you? How would they know you are going to buy it? I guess you are buying right? Or are you renting? If you are renting do you know for sure who the owner is? If you know for sure who the owner is and are paying them, I would ask the former owners to leave the property and not contact you. There's no reason for them to. You could site them for treaspassing or a variety of other issues if they continue to contact you or visit the property.
What does your lease agreement state? How do you know it's in foreclosure? Do you have a lease agreement with this new owner, if you lease agreement states to pay you need to pay. Have you contacted this new owner what do they state?