Fiverr’s term of service states that you must not give any other ways of contact to the sellers outside Fiverr. This not only protect your personal information, but also protect you from being scammed. Fiverr has its own system to protect both sellers and buyers in a reasonable way. Don’t give away your personal details, otherwise you may risk having your Fiverr account banned.
Yes, you should be careful with that as mentioned in Term and Conditions.