US President Donald Trump has kept a low profile on his Scottish golf course, ahead of meetings with top British and European leaders.

Trump arrived on Friday on a visit that has triggered protests in Scotland, with hundreds lining the streets of the capital Edinburgh waving placards saying: "NOT MY PRESIDENT."

The US leader told reporters on arrival that he would visit his two golf properties in Scotland – one in Turnberry on the west coast where he played on Saturday and the other near Aberdeen on the country's eastern coast.

He is also due to meet British Prime Minister Keir Starmer, Scottish leader John Swinney and European Commission President Ursula von der Leyen, whom he called a "highly respected woman".

Von der Leyen headed to Scotland on Saturday, ahead of the meeting, with two top US officials flying in from Washington and officials on both sides expressing cautious optimism that a framework trade agreement could be reached.

"We're cautiously optimistic that there will be a deal reached," an administration source said. "But it's not over till it's over."

EU diplomats say a possible deal between Washington and Brussels would likely include a broad 15 per cent tariff on EU goods imported into the US, mirroring the US-Japan deal, along with a 50 per cent tariff on European steel and aluminium.

The broad tariff rate would be half the 30 per cent duties that Trump has threatened to slap on EU goods from August 1.

Trump will meet with von der Leyen at 1530 GMT on Sunday, the White House said.

President Donald Trump waves to reporters as he sits in his golf cart at the Trump Turnberry golf course. – AP

The US president was spotted on the golf course on Saturday morning, but had no public events on his schedule. Reporters and supporters were kept away by enhanced security.

The White House said Trump was golfing with his son, Eric Trump, and the US ambassador to Britain, Warren Stephens, and his son. White House press secretary Karoline Leavitt was also on the course.

On the trip, Trump will open a golf course near Aberdeen named after his mother, Mary Anne MacLeod, who was born and raised on a Scottish island before emigrating to the United States.

Trump bought the Turnberry property, which includes a hotel and golf course, for $60 million in 2014, in the hope of returning the course to the rotation for the Open Championship, but said his visit was "not about that."

It has not hosted the event since 2009 amid concerns about the lack of accommodation and infrastructure for an event that draws hundreds of thousands.