There are different approaches, it depends entirely on what your strategic goals are for the city. You can drop leaflet propaganda informing citizens to evacuate such as they did in Aleppo [1] and many other places. The premise is simple: give harbor to combatants and you will be treated as such.

Here's a great site that has some leaflets from the Iraq war: [2]

1: https://www.independent.co.uk/news/world/middle-east/syrian-...

2: http://www.psywarrior.com/IraqNFL062.html