Reyes said that his office is "carefully considering the legal implications" of the stay, which was issued about two weeks after a federal court struck down Utah's ban on same-sex marriage.
The attorney general said that the state has little guidance on how to proceed.
"There is no precedent for this," Reyes said at the press conference. "This is precisely the type of uncertainty we were hoping to avoid."
The temporary stay keeps the state from issuing marriage licenses to gay couples while Utah officials appeal the court's ruling. Reyes said that he is working with the plaintiffs' attorneys on an expedited briefing schedule with the appeals court.
County clerks have issued at least 1,000 marriage licenses to gay couples in Utah since the December ruling, according to the Salt Lake Tribune.