Chancellor Angela Merkel's spokesman Steffen Seibert also called Bush a "friend" for Germans, adding on Twitter that "we will never forget his contribution to our reunification".
Clinton added that Bush never stopped serving even after leaving office, working on tsunami relief in Asia and within the US after Hurricane Katrina.
Bush was a foreign policy pragmatist who led the United States through the turbulent but largely peaceful end of the Cold War and the fall of the Soviet Union, which culminated in 1991 with its break-up. The president's casket will lie in state from Monday night until Wednesday morning in the centre of the U.S. Capitol rotunda. "Jeb, Neil, Marvin, Doro and I are saddened to announce that after 94 remarkable years, our dear Dad has died", former president George W Bush said in a statement.
Russian President Vladimir Putin has expressed his condolences over the death of the 41st President of the Unites States George HW Bush, who died on Friday at the age of 94, in a statement published on the Kremlin website. "Share pain of family and American people".
Bush faced a dramatically changing world, as the Cold War ended after 40 bitter years, the Communist empire broke up, and the Berlin Wall fell.
The Trumps add that Bush remained humble despite his accomplishments, "following the quiet call to service that gave him a clear sense of direction".
"On Uganda's and my own behalf, I join the Americans and the rest of the world to mourn the passing of His Excellency George H.W. Bush", Mr. Museveni twitted. The Obamas, in a statement, said Bush's life was "a testament to the notion that public service is a noble, joyous calling".
"George H.W. Bush will be missed and long remembered for his leadership, his decency & his essential kindness", O'Rourke wrote. "And he did tremendous good along the journey".
He leaves behind a legacy of public service matched by few in American history.
The Obamas credited him with "expanding America's promise to new immigrants and people with disabilities". Reducing the scourge of nuclear weapons and building a broad worldwide coalition to expel a dictator from Kuwait.
In a written statement the late president's son, former President George W. Bush, said his father "was a man of the highest character and the best dad a son or daughter could ask for".
In addition to being President and Vice-President, Bush had also served as a Congressman from Texas, U.S. ambassador to the United Nations, director of the Central Intelligence Agency (CIA), and as an envoy to China. The Republican was defeated in his bid for a second term by Democrat Bill Clinton.