"My advice to him would be to tell the truth, I think for a change, and also to cut back on his Twitter feed," he said while appearing on MSNBC.
Carter accused Trump of stonewalling Congress as House Democrats pursued an impeachment inquiry and the White House received criticism over the administration's decision to block U.S. Ambassador to the European Union Gordon Sondland from testifying before the House Intelligence Committee in a closed session.
Both Trump and Republicans have defended the decision, pointing to the partisan nature of the Democrat-led committee.
Carter called on Trump to be more forthcoming with Congress and predicted that the Senate might be willing to remove him from office depending on the type of information that surfaced from the inquiry.
Earlier this year, Trump derided Carter as a "terrible president" after the 95-year-old claimed that Trump won the 2016 election because "the Russians interfered on his behalf."
Carter also expressed support for House Speaker Nancy Pelosi's decision to announce an impeachment inquiry, though he declined to say whether he personally supported impeaching the president.
"I am very glad that the Speaker of the House has ordained that the investigation go forward," Carter said. When Pelosi, D-Calif., announced the inquiry last month, she claimed the Trump administration violated the law by preventing a whistleblower report on Trump's July 25 call with Ukraine's president from being transmitted to Congress.
In a letter sent to top Democrats on Tuesday, the White House made it clear they wouldn't comply with the inquiry.
"Your unprecedented actions have left the president with no choice. In order to fulfill his duties to the American people, the Constitution, the Executive Branch, and all future occupants of the Office of the Presidency, President Trump and his administration cannot participate in your partisan and unconstitutional inquiry under these circumstances," it read.
Fox News' John Roberts and Gregg Re contributed to this report.