To reduce pigmentation caused by acne without scarring, you can try using creams or gels containing tretinoin. These products can help improve skin texture and reduce discoloration. You may also consider chemical peels or alpha hydroxy acid (AHA) treatments to improve skin tone. Consult a dermatologist to determine the best treatment option for your specific needs. Other dermatological techniques like microdermabrasion, hyaluronic acid injections, microneedling, or laser resurfacing are also effective in treating pigmentation issues caused by acne. It is important to seek professional advice to determine the most suitable option for your skin type and condition.