A registered trademark does not automatically require third parties to give up a domain name, but it does give you legal grounds to pursue the matter through established procedures.
The UDRP (Uniform Domain-Name Dispute-Resolution Policy), administered by WIPO, allows trademark holders to challenge domain registrations that are identical or confusingly similar to their trademark, where the domain was registered and is being used in bad faith. A successful complaint can result in the domain being transferred to you or cancelled.
Where the domain holder is actively trading under a name that infringes your trademark, a court action for trademark infringement may also be available. The strength of your case depends on the similarity between the domain and your mark, the similarity of the goods and services, and whether there is evidence of bad faith or consumer confusion.