I have pelvis pain. I have been exercising an it  aggravate it. Why is that?

Depends on where. Pelvic pain can be many things. The bones of the pelvis are fairly strong and stable, except after pregnancy or injury. However, the organs inside the pelvis (ovaries, bladder, uterus, etc) can also cause pelvic pain with bounced around...Such as with exercise. This is certainly worth seeing your doctor for a further evaluation.
Need exam. Many things can cause pelvic pain or pelvalgia. The fact that exercise can exacerbate or worsen your pain leads me to believe there is something wrong. I would go to your nearest obgyn to have an exam. Fibroid tumors are common and can cause pain.