Haseeb Ahmed's video has already received more than 2.5 million views, ITV reported.
The terrorist attack on tourists in the resort of Sousse on 26 June killed 38 people, including 30 Britons.
In the video, Haseeb Ahmed, who works in Birmingham, said:
“I've seen a lot of comments online about how Muslims together haven't actually spoken out much about the atrocities last week.
I urge everyone to condemn these acts. I'm a very proud British Muslim and hopefully everyone should unite and be together and stand against these terrorists who aren't Muslims.
They say that they're Muslims and they recite all these verses taken out of context.
I'm a British Muslim and I condemn these actions, all terrorist actions.
– HASEEB AHMED
In the video, Mr Ahmed, who is originally from Bristol but now lives in Banbury, added: "killing anybody is against Islam".
It says in the Quran killing one person is like killing the whole of humanity.
The majority of Muslims are peaceful people, like myself. You have good and bad in every religion, in every community.
This is a time when people should unite, whether you're Muslim or non-Muslim, you should always condemn these kind of actions.