Garza, 25, expressed an interest last week in playing in MLS. An Atlanta United spokesman declined to comment.
If Atlanta United secures the loan, Garza would join Michael Parkhurst, who has been capped by the U.S. 25 times.
Atlanta United has signed four defenders: Parkhurst, Zach Loyd, Mark Bloom and Mikey Ambrose.
While the team may be adding Garza, it was reported that target Oscar Romero signed a deal with a club in China.
In other Atlanta United news:
The team will open against New York Red Bulls
The team also signed Jacob Peterson