Asked how he felt about the protests, Trump said he was "fine with it".
Timed with his arrival, members of Amnesty UK unfurled a banner reading "Donald Trump: Human Rights Nightmare" opposite the US Embassy.
"I mean, the list goes on", he said.
First lady Melania Trump pulled out all the stops and truly dressed to impress as she and President Trump made their way to a black-tie dinner hosted by Prime Minister Theresa May at Blenheim Palace on Thursday evening.
He added: "We'll see if they're still there in 10 years".
Trump is due to leave Britain on Sunday for talks in Helsinki the following day with Russian President Vladimir Putin, whose government stands accused by May's of unleashing a lethal nerve agent in the city of Salisbury.
Earlier today Trump gave an extraordinary press conference in Brussels after giving North Atlantic Treaty Organisation leaders a bruising over defence cash, where he wrote off protesters and said Theresa May's Brexit deal probably wasn't what Britons voted for.
He has clashed in the past with May - even though she is a fellow conservative who shares his view that defense spending should be hiked - and with her predecessor, David Cameron, who challenged Mr. Trump's anti-Muslim campaign stance as "divisive, stupid and wrong".
Other protests - including several "family friendly" gatherings - will take place at every place he will visit over the coming days. When Trump canceled his plans a few weeks before the big day, some - like London Mayor Sadiq Khan - speculated that the expected opposition scared off Trump and was happy about it.
"It's really kind of irrelevant to what we're trying to do and I don't think certainly it doesn't express the opinion of the British people I met", he said.
"I think they like me a lot in the UK", Trump said in Brussels.
The 'Drag Protest Parade for the Trump UK visit' has been organised by a drag troupe from Manchester, who will be travelling down to London on Friday morning for the event.
However, Mr Trump declared the British people like him a lot, as he began his first official visit to the country.
The declaration was odd given the topic being discussed was whether the President would support a Hard Brexit for the UK.
Trump has been quick to criticize British society, telling a National Rifle Association convention in May that the British didn't have guns but had so much knife crime that one hospital was like a military war zone with its floors awash with blood, a false statement quickly rebutted by British physicians and politicians.
The Police Federation has warned the visit will put "unquestionable pressure" on United Kingdom police forces as tens of thousands of people are expected to protest against the president in London on Thursday and Friday - and in Glasgow on Friday. "I like Boris Johnson, I've always liked him", said Mr Trump.