Pat scallops dry. Heat oil in a large cast-iron skillet over medium-high heat. Add the scallops and cook, flipping once, until browned on both sides, about 5 minutes total. Transfer to a plate and tent with foil to keep warm.
Add tomatoes to the pan and cook, stirring once, until browned on one side and starting to burst, 2 to 3 minutes. Add wine and capers; cook, stirring and scraping up any browned bits, until the wine is reduced by half, about 1 minute. Remove from heat and stir in butter and pepper. Serve the sauce over the scallops, garnished with parsley, if desired.