The Home Office confirmed three Pakistani nationals and an Indian national in their 20s were arrested on suspicion of working illegally after the swoop on Akbar's in Sauchiehall Street.
The officers arrived at 8.40pm on Friday while the restaurant was packed with diners who carried on eating their meals.
A Home Office spokesman said: "Illegal working fuels illegal immigration to the UK and that is why we carry out operations like these.
"If you are a business, you must carry out the correct checks on your staff or you could end up with a heavy fine.
"We work with businesses to let them know what checks need to be made on staff, but those who break the law should know that they will face heavy fines."
Two weeks ago it emerged the Home Office was to be investigated by the equality watchdog over claims of unlawful discrimination after a wave of raids uncovered 130 illegal immigrants, including 24 at Scottish restaurants.
Indian, Bangladeshi, Thai and Chinese workers were put in detention centres awaiting deportation after the UKBA turned up at premises in Tobermory on Mull, Glasgow and Grantown-on-Spey among raids across the UK.