"None of these things are blank checks," Ryan said of his endorsement in a radio interview with The Jerry Bader Show on WTAQ in Wisconsin.
While calling Trump's comments about the Khan family "beyond the pale," Ryan suggested that the remarks from the GOP presidential nominee did not meet his threshold for rescinding his support. However, he said he would continue to call out Trump's campaign and comments as he saw necessary.
The Wisconsin Republican, who presided over the GOP's convention in Cleveland, said it was important to respect the will of the party's primary voters.
"We are a party where the grassroots Republican primary voter selects our nominee," Ryan said. "[Trump] won the thing fair and square."
But he also admitted frustration with Trump's campaign since the conclusion of the RNC.
Ryan also made clear that he isn't interested in Trump's endorsement in his own primary race, where he faces a challenge from Paul Nehlen, a businessman who has aligned himself closely with Trump.
"The only endorsements that I want are those of my own employers here in the first congressional district, and that's really what my focus is," Ryan said.
In an interview with The Washington Post earlier this week, Trump said he wasn't prepared to endorse Ryan, mirroring Ryan's own public handwringing over endorsing Trump earlier this year.