"I am watching with great concern the renewed increase in infection numbers in almost every part of Europe. And I must say the situation continues to be serious,"
"But we have to bear in mind the realities because an agreement has to be in the interests of both sides, in the British interest and in the interest of the EU's 27 member states."
Trump said earlier on Friday that he and his wife Melania had tested positive for COVID-19 and were going into quarantine, upending the race for the White House.
The meeting comes after Tsikhanouskaya met French President Emmanuel Macron on Tuesday in Vilnius, the highest-profile Western leader to meet the exiled opposition leader.
The country reported 2,089 new coronavirus cases on Tuesday, bringing the total to 287,421, with 9,471 fatalities, the Robert Koch Institute for infectious diseases said.
The two sides agreed to open negotiations during a three-way videoconference between Turkish President Recep Tayyip Erdogan, German Chancellor Angela Merkel .
A rise in cases in the last couple of weeks has caused alarm among some virologists and politicians in Germany.
If the numbers go back down we can open up more. If they don't, or rise, we must ask what is needed and in any case a further easing of measures cannot take place now.
The meeting between Macron and Merkel, fresh from striking a game-changing deal for the European Union to raise debt for the first time to fund recovery from the coronavirus pandemic.
Macron has received only a few notable guests at his presidential mansion of Fort de Bregancon in southern France in the past.
Painful discussions resumed "with the possible hopes of a compromise. Nothing has been agreed yet, so I will remain extremely cautious", said Macron as he arrived to the talks.