The app breaches laws in Canada and the Netherlands.
WhatsApp has been accused by Canadian and the Netherlands' data protection authorities of breaching international privacy rules.
Both countries say the application forces users to give access to their complete address book, including both users and non-users of the application.
The application, claimed to be one of the world's top five best-selling apps, is used as an instant messaging application for smartphones including iPhone and Blackberry.
: "Our investigation has led to WhatsApp making and committing to make further changes in order to better protect users' personal information," said Canada's privacy commissioner, Jennifer Stoddart.
Canada and the Dutch Data Protection Authority claim the app breaches laws in both the nations and they will continue to examine WhatsApp. They have said they may enforce penalities if the company does not change its model.
Dutch Data Protection Authority chairman, Jacob Kohnstamm, said that the investigation revealed that users of WhatsApp - apart from iPhone users who have iOS 6 software - do not have a choice to use the app without granting access to their entire address book.
"The address book contains phone numbers of both users and non-users. This lack of choice contravenes (Dutch and Canadian) privacy law," Kohnstamm said.
"Both users and non-users should have control over their personal data and users must be able to freely decide what contact details they wish to share with WhatsApp."
However, the Canadian regulator revealed that the firm is willing to completely comply with its recommendations, while Dutch authorities have said they continue to monitor WhatsApp and will impose fines if it finds the company is breaching rules.