The memo, which was penned by House Intelligence Chairman Devin Nunes and approved for release by the House committee earlier this week, alleges that the Federal Bureau of Investigation (FBI) abused its surveillance tools.
Trump's accusation of the leadership once again maligns people he appointed to their roles, including FBI Director Christopher Wray whom he nominated after firing former FBI Director James Comey in May.
"The top Leadership and Investigators of the FBI and the Justice Department have politicised the sacred investigative process in favour of Democrats and against Republicans - something which would have been unthinkable just a short time ago. Rank & File are great people!" Trump tweeted.
Trump's tweet came as he is set to approve the release of a highly controversial memo accusing the authority in FBI of abusing its surveillance tools during its probe into alleged Russian collusion in the 2016 presidential election, setting up a clash with the intelligence agency.
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The allegation is that the FBI ran surveillance on a member of Trump's campaign.
Earlier, a senior administration official, told reporters aboard Air Force One that the president was expected to tell Congress that he had no objections to the release of the memo.
Requesting anonymity, the official said it is a Congressional process and that the decision was made after looking at the memo the last few days and making sure "it doesn't give away too much in terms of classification".
"I doubt there will be any redactions. It's in Congress' hands after that," the official said, and refused to answer any further questions.
Trump's reported decision comes a day after the FBI in an unusual move went public urging against release of the memo.
Some White House official fear that this might result in the resignation of Wray.
Last year, Trump abruptly fired FBI chief James Comey for his handling of the Russia inquiry.
Trump publicly shamed Attorney General Jeff Sessions for his decision to recuse himself from the Russia case because of his prior contacts with Russia Ambassador Sergey Kislyak.
Once Trump gives his approval, it would be up to the House intelligence committee to take a final call on the report's release.
In a separate statement, FBI Agents Association (FBIAA) president Thomas O'Connor opposed the release of the memo.
"The FBI Agents Association appreciates FBI Director Chris Wray standing shoulder to shoulder with the men and women of the FBI as we work together to protect our country from criminal and national security threats," said O'Connor.
He said the agency's special agents remain professional and focused on protecting the US from terrorists and criminals.