Raised blood pressure is reasonably common in the menopause.
The main factor seems to be that lowering oestrogen can cause the blood vessels to lose flexibility which in turn causes the rise in blood pressure, so the more you go into the menopause the more the symptom can develop.
If you are looking for natural remedies the herbs such as Crataegus (Hawthorn) are used to help maintain healthy BP (although it is very slow and can take several months to show benefit).
Fish oils and garlic are beneficial and it is important to keep salt intake at a healthy level.
Taking a remedy which can gently raise and balance oestrogen may be another way to tackle this so products such as Menopause Support, Black cohosh or Red Clover may be worth trying.