The outing to Trump National Golf Club came hours after Trump tweeted that talks on replacing the law have been going on and "will continue until such time as a deal is hopefully struck."
He added that anyone who thinks the effort is dead "does not know the love and strength in R Party!"
Trump golfed and discussed policy with Paul and budget director Mick Mulvaney, said White House spokeswoman Stephanie Grisham.
Paul came out strongly against the House GOP legislation, and its collapse humiliated Trump in the early days of his administration. After their golf excursion, Paul struck a positive tone, calling it a "great day" with the president.
"I continue to be very optimistic that we are getting closer and closer to an agreement on replacing Obamacare," said the Kentucky senator, who fell to Trump in the 2016 Republican presidential primary.
Trump talked about his efforts to move forward on health care in an interview with the Financial Times published online Sunday. Of the recent defeat, Trump said: "I don't like to lose. But that wasn't a definitive day. They are negotiating as we speak."
Trump said the bill was pulled because "I didn't want to take a vote. It was my idea." And he said that "one way or the other, I promised the people great health care. We are going to have great health care in this country."
It is not clear how a new health care bill will come together, with deep divides among Republicans and little interest in cooperation from Democrats. Since the bill went down, Trump has repeatedly lashed out at members of the conservative House Freedom Caucus who contributed to the defeat.
On CNN's "State of the Union" on Sunday, a member of the caucus, Rep. Jim Jordan, R-Ohio, responded to those attacks. He said "tweets and statements and blame don't change facts. And the facts remain the same. When you look at the document, when you look at the legislation, it doesn't repeal Obamacare."
Trump told the Financial Times that members of the caucus were "friends of mine." But he added: "if we don't get what we want, we will make a deal with the Democrats and we will have in my opinion not as good a form of health care, but we are going to have a very good form of health care and it will be a bipartisan form of health care."