The Glassy Junction pub and grill on Willenhall Road in Wolverhampton let customers in to celebrate Diwali on Saturday evening, West Midlands Police said.
Officers were called to reports of lockdown laws being broken at the former Malt Shovel pub at around 9.30pm.
When they arrived they found that drinks were being served and fireworks had been set up outside despite all hospitality venues being banned from operating under the current one-month lockdown in England.
The venue has been operating as an Indian takeaway during the lockdown, which is permitted so long as businesses close by 10pm.
Fifteen people were issued with Fixed Penalty Notices and the pub was fined £1,000 for the breach.
A spokeswoman for West Midlands Police said: "Fifteen people were issued with Fixed Penalty Notices after we were alerted to a breach of lockdown regulations at the Malt Shovel pub.
"Officers attended the premises which has been operating as a takeaway, at just before 9.30pm on Saturday and found some customers had been let in to celebrate Diwali.
"Fireworks were set up in a yard outside ready to be let off and drinks were being served.
"The venue was also fined £1,000 for breaching lockdown regulations."