Peralta, a relief pitcher with a 0-2 record and 3.72 earned run average, said he would appeal the disciplinary action so is eligible to continue playing until the process is completed.
Peralta was tossed from Tuesday's game in Washington before he even threw a pitch. He was announced into the game and Nationals' Manager Davy Johnson immediately went to the umpires to have Peralta's glove checked.
Umpires found "a significant amount" of pine tar on the inside of the glove, crew chief Tim Tschida said. Peralta was ejected from the game and his glove confiscated.
The Rays won the game 5-4.
Peralta formerly played for the Nationals and it was suspected some of his former teammates may have suggested to Johnson that pine tar was on the glove.
Tampa Bay Manager Joe Madden called Johnson's move "cowardly."
Peralta was used in Wednesday's game against the Nationals, retiring the two batters he faced while using a different glove.