Possibly, but not without checking first — the NHS specifically lists blood-pressure-lowering medicines among the drugs to tell your doctor or pharmacist about before you take melatonin, so clear the combination with them rather than assuming it's fine.
The NHS names "medicines that lower blood pressure" as one of the categories you should flag to a doctor or pharmacist before starting melatonin, because the two may affect each other. Melatonin can also cause dizziness and drowsiness on its own, which may add to what a blood-pressure medicine is already doing. NCCIH notes short-term melatonin appears safe for most people but that anyone taking medication should consult their health care provider first, and that melatonin can stay active longer in older adults (who are also the people most likely to be on blood-pressure drugs). The cited sources do not name a specific blood-pressure drug or quantify the interaction, so the safe course is simply to check before combining them.
Talk to your pharmacist or prescriber before combining them, and tell them exactly which blood-pressure drug you take. Use the lowest effective melatonin dose, take it at bedtime, and don't drive or operate machinery if it makes you drowsy, dizzy, or clumsy. Watch for lightheadedness or dizziness on standing (a sign your blood pressure may be running low) and for blood-pressure readings that seem higher or more erratic than usual — report either to your clinician. The NHS advises against drinking alcohol with melatonin, because together they can make you sleep very deeply so you do not breathe properly and can have difficulty waking up. Be extra cautious if you are older, have liver or kidney problems, or also take sedatives, antidepressants, or blood thinners, and check first if you are pregnant or breastfeeding. This is general information, not a substitute for advice from your own pharmacist or doctor, who can review your specific medicines and health.
This is general reference, not medical advice, and not a guarantee of safety. Interactions depend on your doses, health conditions, and other medicines. Always confirm with your pharmacist or doctor before combining products, and follow the dosing on each label.