The Dodgers said X-rays were negative and that Ramirez's status was day to day.
Ramirez tore a tendon in the thumb of the same hand diving for a ball in the World Baseball Classic in 2013.
Ramirez was bending over to field Corey Dickerson's ground ball when the ball skipped and went off the knuckles of his right hand and into center field for what proved to be a double.
Dodgers trainer Stan Conte examined his hand as Ramirez squirmed in apparent pain before the two walked to the dugout.
Ramirez hit his 11th home run earlier in the game and was beginning to get on a roll, with 27 RBIs in his past 31 games.
Dodgers manager Don Mattingly estimated that Ramirez would miss "a couple of games" but said he was only guessing and that the team will wait to see how Ramirez's swollen fingertip responds to treatment Wednesday.
"We're playing better, and you don't want to see one of your middle guys get hurt," Mattingly said. "He was swinging well, and you don't want to see anything happen to anybody. We're getting close to getting back to full strength. Juan [Uribe] should be back soon, and you don't want to see it go back the other way."
Uribe, on the disabled list with a strained hamstring, is expected to begin a minor league rehabilitation assignment with Class A Rancho Cucamonga on Thursday.