Ryan told reporters on Capitol Hill that he "laughed out loud" when he watched Trump say on Tuesday night that he would "pay a big price" if the two of them didn't get along.
"Sometimes reality is stranger than fiction around here these days. I don't really think anything of it. I don't really know him," Ryan said at his weekly press conference, adding, "We're going to obviously get to know each other if he gets the nomination. And we'll cross those bridges if we get to it. I'm a good-natured guy so I get along with everybody."
Ryan had a private dinner with Romney in Salt Lake City Utah last weekend, CNN has learned. The speaker was out West on a campaign swing for House candidates, according to an aide.
But a Ryan aide declined to say whether the 2016 race came up in their conversation and maintains the speaker only learned on Wednesday night that Romney was planning to deliver a speech denouncing Trump and urging Republicans to reject his candidacy.
As he does regularly when asked about the 2016 race, Ryan held up his "unique role" as chairman of the national convention in July as the reason he won't wade into the swirling debate about Trump's potentially damaging impact if he is at the top of the ticket in November.
"Here's what I can control. If I see episodes where conservatism is being disfigured. If I see ideas and comments that mislead the people as to who we are as Republicans I'm going to speak out on those," Ryan said, noting he made a point earlier this week to criticize Trump's failure to immediately denounce white supremacist groups.
Trump's campaign reached out to the speaker's office, but the two have not yet spoken, according to Brendan Buck, spokesman for Ryan.
The speaker emphasized on Thursday he planned to brief all of the 2016 presidential candidates on his effort to map out a detailed policy agenda for the general election.
"I can help put substance in this campaign. The way we see out role in this campaign through our agenda project is to add a heel and a rudder on this ship of the Republican party and give it direction so we can take the American people a real choice."
Ryan says he wishes he and Romney did a better job laying out the contrast in the 2012 election.
Asked if believed Trump would actually take up his policy prescriptions, Ryan said, "We'll see when we have a nominee."
Trump to date has won endorsements from a handful of Republican House members and GOP Sen. Jeff Sessions of Alabama. On Thursday Sen. Bob Corker of Tennessee, a close ally of Senate Majority Leader Mitch McConnell, expressed sympathy for enthusiasm being generated by the Trump campaign, if not the candidate himself.
"Here's my message to the Republican Party leaders: Focus more on listening to the American people and less on trying to stifle their voice," Corker said in a statement.
"What's happening in the Republican primary is the result of two things: the fecklessness and ineptness of the Washington establishment in failing to address the big issues facing our country and years of anger with the overreach of the Obama administration. And to be candid, I think the American people should be angrier than they are."