The moves were made before Wednesday night's game against Tampa Bay.
Kubitza was scheduled to make his major league debut Wednesday, filling in for David Freese, who left Tuesday night's 8-2 win over the Rays with right hamstring tightness.
"Right now it looks like it's something that's very manageable," Angels manager Mike Sciosica said of Freese's injury. "Hopefully, we're talking a matter of days, but whatever it takes, it takes."
Freese, hitting .239 with nine homers and 32 RBI in 58 games this season, extended his hitting streak to 12 games Tuesday,
Nieuwenhuis hit .136 in 10 games with the Angels.