The Angels claimed Friedrich, 28, off waivers from the Rockies two weeks ago.
The Angels said Friday night that a physical raised concerns over "Friedrich's ability to play at his accustomed level." The commissioner's office then allowed the Angels to send Friedrich back to Colorado.
A left-hander, Friedrich is 5-16 with a 5.81 ERA in parts of three seasons with the Rockies.
The move leaves the Angels with an open spot on the 40-man roster.