"Our relationship with Russia has NEVER been worse thanks to many years of US foolishness and stupidity and now, the Rigged Witch Hunt!" Trump tweeted, referring to US special prosecutor Robert Mueller's probe.
Last week, Mueller indicted 12 Russian intelligence officers accused of hacking computer servers belonging to Trump's 2016 election rival Hillary Clinton and her Democratic Party, then leaking private emails to damage her campaign, AFP reported.
Trump has furiously denied his campaign colluded in the alleged interference, and has generally denounced the special investigation as a "witch hunt" promoted by his enemies to delegitimize his victory.
At the same time, the US leader has promised to bring up the issue on Monday at his summit with Putin in Helsinki.