About 200 people attended the "Pittsburgh Not Paris" event, which took its name from an assertion Trump made that he was elected to "represent the citizens of Pittsburgh, not Paris."
Demonstrators chanted "Pittsburgh not Paris" and "jobs, jobs, jobs" to show their support for the president.
On Thursday, Trump announced the U.S. would withdraw from the international agreement in a speech in the Rose Garden. He said he would also be open to renegotiating U.S. participation in the accord, which European leaders have said is not an option.
"The fact that the Paris deal hamstrings the United States while empowering some of the world's top polluting countries should dispel any doubt as to the real reason why foreign lobbyists wished to keep our magnificent country tied up and bound down by this agreement," Trump said in his speech. "It's to give their country an economic edge over the United States. That's not going to happen while I'm president, I'm sorry."
Trump's decision to withdraw from the Paris Accord was widely condemned by many international leaders, U.S. companies, Democrats and many American citizens. But those who voted for Trump praised him for doing exactly what he was elected to do.
During his speech, Trump argued that there the accord would have a negative economic impact and cost America jobs, claims that many economists have disagreed with.
Trump also plegded to "exit or renegotiate any deal which fails to serve America's interests."
Anti-Trump "March for Truth" events were also held in cities around the country on Saturday, with protesters calling for an investigation into the Trump Administration's alleged ties to Russia and demanding that he release his tax returns.
"The legitimacy of our democracy is more important than the interests of any party, or any president," "March for Truth" organizers wrote on their website. "So, we will rise together to call for a fair and impartial investigation, for the pursuit of truth, and for the restoration of faith in our electoral system and the Office of the Presidency."