iPhone 4 locked by it's previous owner iCloud account
No.

You need to contact the person who sold you the phone and get them to either give you the iCloud details, or give you your money back.

The phone can not be activated by Apple until it has been unlocked using the iCloud details (login and password) that it was locked with. This is a security measure to stop stolen phones from being useful to people.

If the seller does not have the iCloud details, then it was probably not their phone to sell, and they should return your money.

Sorry.