Jets from the North American Aerospace Defense Command, or NORAD, had to be scrambled to intercept a small plane near the Trump National Golf Club in Bedminster, New Jersey, on Saturday afternoon.
The plane was not responding to communication, according to authorities.
The Secret Service added, "The President was not in danger and the security of the complex was maintained throughout. Further investigation of the airspace violation is pending."
The president is spending a second straight weekend at his golf club. On Friday evening, he delivered a speech to a large group of police officers from the New York City Police Benevolent Association at the country club.
Trump is expected to deliver a press conference at Bedminster on Saturday afternoon. Last weekend he used the site to deliver remarks and sign four executive actions targeted at helping recovery from the COVID-19 pandemic.
ABC News' Luis Martinez contributed to this report.