The protesters, mainly women gathered at the Trump National Golf Course in the US State of New Jersey, where the tournament took place.
The demonstrators were wearing anti-Trump T-shirts, the Hill newspaper reported.
President Trump visited the US Open yesterday for a third time in a week as he was in attendance both on Saturday and Friday and even thanked his supporters for "out-numbering" the protesters, Sputnik reported.
"I am at the @USGA USWomensOpen. An amateur player is co-leading for the first time in many decades - very exciting!," the US president wrote on Twitter on Monday.
The protest against the president regularly takes place both in the US and abroad, when Trump pays an official visits to the foreign countries.
Trump was criticized by his opponents over his decisions in the sphere of environment, migration as well as for the repeated offensive comments related to women.
Last week amid Bastille Day celebrations, many people took to the streets of Paris to protest against Trump's visit to the French capital. (ANI)