Cleveland will be adding outfielder Russ Canzler and reliever Scott Barnes from Triple-A Columbus, and promoting outfielder Thomas Neal from Double-A Akron. Neal is not on the team's 40-man roster, so a subsequent move will be required to clear room.
"The rest will come after the season is over in Columbus," Acta said.
The Triple-A season officially ends for the Clippers on Monday.
Canzler -- acquired in a trade with Tampa Bay in January -- has hit .265 with 22 home runs and 79 RBIs in 130 games for Columbus. He spent three games with Tampa Bay in September 2011.
The left-handed Barnes, who posted an 8.10 ERA in seven games in two previous stints with the Tribe this season, has appeared in 31 games for Columbus. Over 52 Minor League innings, he posted a 3.98 ERA, with 67 strikeouts.
Neal -- making his big league debut -- hit .314 with 12 homers, 24 doubles and 51 RBIs in 117 games for Akron.
Acta said that Cleveland tries to balance "reward" callups with promotions that allow players to get a good look over the final month. Given the Indians' place in the standings, the club will likely add players who will be under review for the final four weeks of the season.
"It's a combination of it," Acta said, "but the guys that are coming up are going to be getting some at-bats, the majority of them are going to be getting some at-bats. So it's not so much rewarding, but also evaluation time for us."
Other options on the 40-man roster are starter David Huff; relievers Frank Herrmann and Scott Maine; infielders Lars Anderson, Cord Phelps and Juan Diaz; and catcher Luke Carlin. Some options not on the 40-man roster are infielder Jared Goedert, along with outfielders Tim Fedroff, Aaron Cunningham and Shelley Duncan.
"A lot of things go into it," Acta said. "Some guys can have a very good year, but if they're not on the roster, and you don't have a spot, you can't add them."