Measuring your blood pressure while being anxious about your blood pressure might be not good for your blood pressure.
Frankly, I wouldn't be too worried about a high blood pressure alone barring you from breath-hold diving. I have an similar blood pressure, and I am still diving.
There does exist medication that you can use while freediving, if you would need it in the future.
Do you have any other ideas why you would get a an high blood pressure? If stress is an factor, I would recommend to try to deal with that. There are also other lifestyle options that could lower your blood pressure, but that is something for your general physician to discuss with you.
I don't really fit in the category of people to have high risk for high blood pressure. My parents weren't affected and as I said I'm average weighted with low body fat, young, don't smoke anymore, don't drink alcohol at all (maybe 1-2 beers in a month), do regular weightlifting, get outside everyday for walks with my dog, don't have a stressful job, definitely eat more healthy than the average 25 year old male....