Soria said after Sunday's game that the Royals had not indicated when he might come off the disabled list.
"They haven't told me anything," Soria said. "I'm going with them [to St. Petersburg], and that's good."
The Royals open a three-game series with the Rays on Tuesday night. Soria has not pitched since May 7 because of a sore right shoulder, but after appearing in two games last week at extended spring training in Arizona, he reported no soreness.
Soria returned to Kansas City on Sunday, but was not activated for the game against the White Sox.
After the Royals' relievers lost a second straight game to the White Sox, manager Trey Hillman said he thought Soria's return would give the bullpen a boost.
"There's no doubt," Hillman said. "It certainly helps the confidence level, first and foremost. Getting guys back to what is more consistent roles and knowing you have him to bring into a tie ballgame like we would have today in the ninth inning. Or certainly in save situations. It's just a confidence boost along with what he brings to the table physically."
Soria has pitched in just eight games this season with seven saves and a 2.08 ERA. Last year, he posted 42 saves.
Hillman also hopes to get center fielder Coco Crisp back in the lineup on Tuesday night. Crisp has missed the past four games because of a sore right shoulder.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.