@Prisoneer 

If you select the rule menu item on the left it will provide an example on allowing www.google.com only. In your case, you can do the reverse so you would set the access control for Allow, and for the target, you would select the dropdown list and select URL, and add those URLs. What should happen is the router will allow all packets except those mentioned to filter which should be those two sites.

@Tony Thank you for the answer
 

I have already done that. But every time when I turn on my TV, I see this annoying "There is a new update" reminder. What should I do in order to block that?
 

@Prisoneer 

There looks to be a newer firmware for your routers region: link

Upgrade instructions: link

After the update see if the traffic is blocked.

If the TV doesn't need to access the internet but rather uses something different like a FireTV or Chromecast to stream video you can look to block any traffic to see if that prevents the TV from reaching out to queue for an update.