If looking for smome clam beach go to Awas Beach , if looking for water sports activity then Kihim and Kashid is good. You can also visit Birla Temple close to this place.
If you really want to go any beach nearby Pune then should go only for Diveagar Beach which js veru much better than Kashid beach and Alibaug beach. They have black sand water and not good place nowadays. Still you can visit there if you want then go to Sunset Point, Kashid Beach and if you have more time then go to Murud Janjira Fort.
You can try adventure water activities near kashid beach. And near alibag you can visit murud Janjira Fort .Also less known devghali beach near kashedi