If they parallel park in spots along the 500 block of North Main Street, their car could get towed.
Between the hours of 10 pm and two am Thursday through Saturday, the spots are reserved for party buses picking up people outside the bars.
But some drivers say the signs are too tall, and they can't see the fine print.
The city says the new signs have an orange flag to catch people's eye.
Bloomington Police Spokesman Dave White said the change prevents traffic tie ups on the street.
"The buses were double parked on the street, nobody behind them could get by, so you had traffic behind the them being blocked up and jammed up down there, plus all of the people," White explained. "When you look at two am as bars are letting out you could have 1,000 people on that roadway all crossing at the same time."
The change went into effect about a month ago.
Police say during the first weekend violators were only issued warnings.
They hope the message sinks in soon.