Monitor connected to MacBook Pro using Thunderbolt 3 USB-C cable not charging the laptop

I have LG 34UM69G-B Monitor. I am using USB-C Thunderbolt 3 cable to connect MacBook Pro 13 2018 to Monitor. Display and audio works as expected but it does not charge. It shows as follows if I click the battery icon on the MacOS.

Battery Not Charging

Power Source: Power adapter.

I don't understand why its not charging? I tried searching in the internet for solution but couldn't find anything. I just don't know if the issue is with the monitor/cable or laptop port (not sure if I have to reset it).

I suspect it's the monitor. It may not be able to output enough wattage to charge the laptop but again I am not sure. If anyone has an answer, please let me know.