The US president said he hoped the Organisation of the Petroleum Exporting Countries, which is meeting on Thursday, would “be keeping oil flows as is, not restricted”.
He added: “The World does not want to see, or need, higher oil prices!”
The Twitter post came as dignitaries began to arrive at Washington’s National Cathedral for former president Mr Bush’s funeral on Wednesday afternoon.
In an earlier tweet, Mr Trump said he was “looking forward to being with the Bush family” at the service, scheduled to begin at 11am local time (4pm GMT.)
He added: “This is not a funeral, this is a day of celebration for a great man who has led a long and distinguished life. He will be missed!”
Minutes earlier, he had tweeted about about his hopes for an end to a trade war with China, writing that Beijing was sending “very strong” positive signals. He added: “Not to sound naive or anything, but I believe President Xi meant every word of what he said at our long and hopefully historic meeting.”
Mr Bush is said to have ensured Mr Trump would be invited to his funeral, reportedly saying before his death he did not want to “stiff a sitting president” despite tensions between him and the Bush family.
Mr Trump met the late president’s son, George W Bush, on the eve of his father’s funeral. The American leader travelled 230 metres to the meeting at the Blair House presidential guest house in limousine with a motorcade.
Nearly 3,000 people, including every living US president and many other world leaders, were scheduled to attend the funeral.
The service was preceded by three days of mourning during which Mr Bush’s body lay in state at the Capitol Rotunda.
His funeral procession will pass the White House and the US Naval Observatory, two landmarks in the former president’s life and career.