Srettha said he was saddened by the news, adding that such events should never happen and hoped for Trump's safety.
One person was killed in the shooting and two seriously injured, while the shooter was gunned down by the Secret Service. The FBI later called it an assassination attempt against the former president and candidate for the 2024 presidential election.
Speaking from Chiang Rai province on Sunday, Srettha said that such acts of violence were of great concern, especially considering Pennsylvania's significance to the Republican Party.
The prime minister said the Ministry of Foreign Affairs had yet to provide an official report, and that he had been following updates from BBC and social media.
He acknowledged that similar incidents of political violence had occurred in Japan and the United States, recalling the assassination attempt on President Ronald Reagan, who had to undergo surgery, but whose press secretary was paralysed.
When asked about increasing security measures during public appearances for Thai prime ministers, Srettha said the security environment in Thailand and the US were different. He affirmed his belief that Thailand's security system was adequate and left the matter to the discretion of the security agencies.