“We have grave concerns about the material omissions of fact that fundamentally impact the memo’s accuracy,” the FBI said in a statement.
The White House has reportedly indicated that it could be published on Thursday.
Democrats claim the memo is an attempt to discredit the FBI-led Russia probe.
The White House has to approve the top-secret memo’s release.
“It will be released here pretty quick, I think, and the whole world can see it,” White House chief of staff John Kelly said during an interview with Fox News Radio on Wednesday.
Hours later, the FBI issued a rare statement saying that it had had “limited opportunity” to review the document before the House Intelligence committee voted to release it on Monday.
“We are committed to working with the appropriate oversight entities to ensure the continuing integrity of the FISA (Foreign Intelligence Surveillance Act) process,” the FBI statement added.
On Wednesday night Democrats on the committee accused the Republicans of secretly altering the memo before giving it to the White House.
Representative Adam Schiff said the document had “material changes”, meaning it was not the same as the one that had been voted on. He said it should be withdrawn and re-reviewed prior to any possible public release.
The four-page memo, which was compiled by staffers for the House Intelligence Committee Chairman Devin Nunes, claims that the Department of Justice abused the surveillance programme known as FISA to unfairly target a member of the Trump campaign.
According to lawmakers who have reviewed it, the document purports to show that the agency obtained a warrant to spy on a Trump campaign aide after submitting as evidence the unproven “Russian dossier”.
That dossier was compiled by former British intelligence agent Christopher Steele with money financed in part from the Hillary Clinton campaign.
The committee voted to release the memo earlier this week, and Mr Trump has until the weekend to decide whether to de-classify the information for public release. (Courtesy BBC)