"If I see ideas and comments that mislead the people as to who were are as Republicans, I'm going to speak out on those," Ryan said today at his weekly news conference.
Ryan has twice rebuked Trump previously -- though not by name -- for his proposed ban on Muslim immigrants and for declining to distance himself from white supremacists in an interview last Sunday. (Trump later blamed a faulty earpiece and disavowed support from former Ku Klux Klan leader David Duke and the white supremacist community.)
The Wisconsin Republican said Thursday that his role as House Speaker -- and as chairman of the party's nomination convention -- is not to challenge Trump, but to "help put substance in this campaign" as the leader of the House Republican conference.
"I can help lead House Republicans to offer an agenda," Ryan said. "The way we see our role in this campaign ... is to add a keel and a rudder to this ship of the Republican Party and give it direction."
He said Republicans did not do a good enough job in the 2012 campaign of giving voters "a very clear choice."
Ryan said he doesn't know Trump well, but is planning to touch base with the New York businessman (and the other remaining candidates) in the near future to discuss the forthcoming House GOP agenda.
Asked if he believes Trump will sign on to the planned House Republican agenda should he win the GOP nomination, Ryan said "we'll see when we have a nominee."
Ryan said he "laughed out loud" Tuesday night when Trump, in his Super Tuesday victory speech, said Ryan would "pay a big price" if they are unable to work together, provided Trump wins the White House.
"Sometimes reality is stranger than fiction these days," Ryan said, adding that he believes he would get along with Trump.
"I'm a good-natured guy, so I get along with everybody," he said.