Feinstein said in a statement Tuesday that she released the testimony to counteract "innuendo and misinformation" about the co-founder's testimony.
He then said Feinstein, who is seeking another term, "Must have tough Primary!"
Trump also repeated that the investigation into Russian interference in the 2016 USA election is a "Witch Hunt" and says "Republicans should finally take control!"
A Grassley spokesperson, in a statement, called Feinstein's release of the transcript "confounding" and said her action "undermines the integrity of the committee's oversight work and jeopardizes its ability to secure candid voluntary testimony relating to the independent recollections of future witnesses".
Sen. Dianne Feinstein (D-CA) released the transcript of the closed-door interview that Glenn Simpson, the founder of the private intelligence firm that assembled the so-called Trump-Russia dossier, gave to the Senate Judiciary Committee in August. "Republicans should finally take control!" Chuck Grassley. She is the top Democrat on the panel.
Alabama Leading Rusher Damien Harris To Return For Senior Season
Having been thoroughly prepared for that next step, I am truly ready, because in the beginning, I chose THE RIGHT SCHOOL. Get prep sports breaking news alerts from the Gwinnett Daily Post staff delivered to your email.
In a separate Tweet, Trump referred to the Russian Federation investigation as the "single greatest Witch Hunt in American history".
The lengthy transcript was released over the objections of Republicans, who have been sharply critical of Simpson's firm, Fusion GPS.
Fusion GPS hired former British spy Christopher Steele during the 2016 campaign to put together an infamous Trump-Russia 35-page dossier that was first published by BuzzFeed a few days before his inauguration in January.
"There was no collusion, everybody including the Dems knows there was no collusion, & yet on and on it goes", he wrote in a separate Tweet.
"It's totally confounding that Senator Feinstein would unilaterally release a transcript of a witness interview in the middle of an ongoing investigation - a witness that Feinstein herself subpoenaed a year ago for lack of cooperation", Grassley's press secretary said in a statement. Grassley said he was "confounded" by the release and argued that it could undermine attempts to get additional witnesses. In addition to looking into whether members of the Trump campaign colluded with Russian Federation to tilt the election in his favor. special counsel Robert Mueller is also examining whether Trump sought to obstruct justice when he fired Federal Bureau of Investigation director James Comey last May.