The short answer
Yes, mostly in the Palmeraie on the city's northern edge. Club Med Marrakech La Palmeraie has a Family Oasis pool with slides and a paddling area, kids' clubs from 4 months to 17 years, and day passes. Other Palmeraie resorts offer lifts, gated shallow-end pools and ground-floor family rooms.
In more detail
The Palmeraie, the old palm grove on the northern fringe of the city, is where the big resort hotels sit. For a trip where the pool is the whole point, they trade medina atmosphere for conventional convenience: lifts, gated pools with shallow ends and ground-floor family rooms.
Club Med Marrakech La Palmeraie is the clearest kids' club option in our venue notes. It is an all-inclusive resort with a buffet and a Moroccan à la carte restaurant, a dedicated Family Oasis pool with slides and a paddling area, and kids' clubs running from 4 months to 17 years. It is also open by day pass. Beldi Country Club, a 12-hectare estate on the edge of the Palmeraie, has swimming pools among olive-tree gardens.
Day-pass resorts suit medina families too. Garden restaurants and day-pass resorts around the Palmeraie let a family staying in a riad combine lunch with a proper swim in the heat of the day.
If you want the medina and a pool, a riad with a plunge pool works, but check depth and fencing first. Tell us the children's ages and we will suggest bases that fit.