Liverpool manager Jurgen Klopp has asked fans to "show respect" outside Anfield before Tuesday's Champions League tie against Roma, and not throw objects at the visiting team's bus, reports BBC Sport.
Cans, bottles and flares were thrown at Manchester City's bus as it arrived at the ground before the first leg of their quarter-final earlier this month.
"This is an outstanding club known for its fantastic atmosphere," said Klopp on the eve of the semi-final first leg.
"We don't need to throw things."
"In the stadium do it again and better," added Klopp. "Outside the stadium, please show the respect we have to show.
"We can show how wonderful Liverpool people are and we can show it in 20 minutes before the game and then the whole world knows it."