Liu, who was China's most prominent human rights and democracy advocate, died yesterday at age 61 from liver cancer. He had been serving an 11-year prison term for "subversion".
61-year-old Liu was awarded the 2010 Nobel Peace Prize while in jail.
"President Donald J Trump was deeply saddened to learn of the passing of Nobel Peace Prize laureate and prominent Chinese political prisoner Liu Xiaobo," White House Press Secretary Sean Spicer said.
Just a day before Liu's death, the US had called on China to release him from custody so he could see his family and pursue the medical care.
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Several American Senators expressed their sorrow over Liu's death.
"Today the world lost a hero of liberty and freedom," said Senator Ted Cruz, the Republican Senator from Texas.
"Ever since leaving the safety and comfort of America to lead the protests at Tiananmen Square in 1989, Liu sealed his fate as a persistent focus of persecution from the authoritarian PRC (People's Republic of China)," Cruz said.
Senator John McCain said the death of Liu in a Chinese prison represents an egregious violation of the fundamental human rights for which he spent his life.
"Unfortunately, and as Dr Liu would have wanted everyone to remember today, this is only the latest example of Communist China's assault on human rights, democracy, and freedom," he said.
McCain said that the Chinese government's delay in his treatment was the last "barbaric" violation of Liu's human rights.
He said the Chinese government must give Liu's remains to his family and grant his wife an exit visa to leave the country.
"There should be an independent investigation into the circumstances surrounding Dr Liu's death, his treatment in detention, the timing of the diagnosis of his late-stage liver cancer, and countless other questions that need to be answered, he said.