While Marrakech is a very safe city, we must warn that if you have never visited a North African countries you may probably have some sense of insecurity because, although there are enough tourists, its labyrinthine medina can become intimidated.
If you stay within the medina, the walk to the riad at night may not be very pleasing to the majority. Main street lights are fairly low, some smaller streets have no lights, & sometimes you even light your way with your mobile phone.
Add to this that there are people lying in the corners, and even a child who will follow you to the riad demanding money, obviously it s not what you are expecting.
No doubt this is the least we like Marrakech. If you want help you can always choosed at a hotel outside the medina and take a taxi at the Place Jamaa el Fna, but missing the experience of the riad is a shame.
During the day things change radically and you feel calmer, with light and a lot more people on the street everything is different.
Plainly speaking, in Marrakesh is not going to happen to you anything bad, many people can you ask for money on the street and sure there are pickpockets around the square, but they’ll never threatened by the fear of the police and their laws.