How do I decrease the saltiness in pork meatballs?
The easiest way to make the taste of the meatball less salty is to make the tomato sauce a bit sweeter than you normally want it. 

Another option is to make the sauce a bit spicy. Both sweetness and spiciness will lower your tongue's perception of saltiness.

Note that it will not make the meatballs noticeably less salty themselves. This only hides the saltiness, so if you are trying to lower the sodium due to dietary restrictions, this will not help in that regard. 

If the meatball is so salty that the sweet/spicy sauce doesn't mask it, you can re-purpose the meatball in other ways. Some ideas include:


Break them up into little pieces and sprinkle on top of a salad (treat it like how some people treat bacon bits in a salad).
Try eating the meatballs in a sandwich with the sweet/spicy tomato sauce. Sandwich bread is very neutral in taste and can help with the saltiness.
Break into bits and add into a baked pasta dish.
Add it into a vegetable or noodle soup.