You can dim LEDs very effectively by just reducing the current. It does not have to pulsate.
The lamp will have several strings of LEDs. I guess that it will have strings of 10 LEDs, totalling about 32 V, and each string has a LM317T to limit the current. There will be 20 strings like that, each taking about 0.3 A.
If you reduce the current to the entire lamp, it is likely that some strings will dim before others, because the LED voltages will be different. Even if all the LEDs are rated at 3.2 V, some might be 3.1 V and some 3.3 V, so the total voltage of a string could easily be 31.5 V or 32.5 V. If you reduce the current, the voltage will reduce, and it will reduce for the higher voltage strings first.
That is why many circuits turn the power to such a lamp on an off very quickly. That gets over the problem of some turning on before others, but introduces the problem that flicker may be visible, depending on lots of factors, including who is looking at it. Some people are much more sensitive to flicker than others.
If you want to reduce the current in each string of LEDs, you would need to post the existing circuit diagram.