i want to block urls in comments.

If you don’t want any URLs, the simplest change is to update your settings to allow a different number of links.

i try it but it dose not stop urls in comment.

The comment won’t be stopped, but it will not be published. You can also try a plugin – there are plenty of them out there.

Insall Akismet, Its free.
It autmatically detects spam comments and filters them.