Contrary to the common myth, a regimen consisting of a mixture of strength and endurance training—as you are doing—will generally lead to a loss of fat mass, and a corresponding gain of fat-free (muscle) mass. Far from being an unattainable or theoretical ideal, it is the norm, provided that your diet is neither excessively restrictive nor overabundant, and provided that you are consuming adequate protein.
Some commentators will dispute this fact, perhaps citing the First Law of Thermodynamics along with some fallacious reasoning:
“The Law of Conservation of Energy states that ‘energy inside an isolated system is constant; energy can neither be created nor destroyed’. Since a loss of fat mass requires energy output, and a gain of muscle mass requires energy input, an energy deficit is required to burn fat, and an energy surplus is required to build muscle.”
The problem with such reasoning is that adipose and skeletal muscle tissues represent two distinct functional systems which are connected, but not isolated, and which form just a part of a much larger system—the body. The processes of aerobic respiration are entirely independent of those of hypertrophy. And whilst they involve some of the same resources, they are in no way mutually exclusive.
Moreover, this belief contradicts literally hundreds of studies that have observed simultaneous fat loss and muscle gain in different demographic groups. The phenomenon has been observed in untrained women and men, obese women (including those who performed exercise alone) and men, older women and men, well-trained male masters endurance athletes, college football players, elite rugby players both developing and professional, elite male artistic gymnasts, and elite power athletes more generally.
For ideal results, strength training should be complemented with high-intensity endurance training, and combined with a high-protein diet of between 1.6-1.8 grams per kilogram of lean body mass, per day. If the body is in significant energy deficit (up to ~40%), as much as 2.0 grams per kilogram per day may be warranted. Long endurance work will accelerate losses in fat mass, but will also limit muscle gain, so it should be moderated.
I hope that helps.