President Trump warned the Kremlin on Wednesday not to retaliate against any U.S. strike on Syria in the aftermath of a deadly chemical weapons attack orchestrated by the Assad regime.

In a morning tweet, Trump referred to Syrian President Bashar Assad as a "Gas Killing Animal" and rebuked Russia for being "partners" with the Middle East strongman.

“Russia vows to shoot down any and all missiles fired at Syria,” Trump wrote. “Get ready Russia, because they will be coming, nice and new and ‘smart!’ You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!”

Trump’s comments follow remarks from Russia's ambassador to Lebanon, who reportedly said told a Hezbollah television station Tuesday that Russia would shoot down American missiles fired at Syrian government targets.

"If there is a strike by the Americans, then...the missiles will be downed and even the sources from which the missiles were fired," Ambassador Alexander Zasypkin told Hezbollah's al-Manar television station.

Trump is scrapping plans to travel this week to a summit in South America due to the situation in Syria, the White House said Tuesday.

Trump on Monday called the weekend chemical attack in Syria “atrocious” and said the U.S. will make “major decisions” about its response soon.

On Monday, the president said he isn’t ruling out military action.

“Nothing is off the table,” Trump said.

Saturday's suspected poison gas attack took place in a rebel-held town near Damascus amid a resumed offensive by Syrian government forces after the collapse of a truce. Syrian activists, rescuers and medics said the attack in Douma killed at least 40 people, with families found suffocated in their houses and shelters.

In a series of other tweets Wednesday, the president lamented the state of the U.S. relationship with Russia and blasted Special Counsel Robert Mueller’s investigation as “corrupt.”

“Our relationship with Russia is worse now than it has ever been, and that includes the Cold War,” Trump said. “There is no reason for this. Russia needs us to help with their economy, something that would be very easy to do, and we need all nations to work together. Stop the arms race?”

In another tweet, Trump argued his administration is “doing things that nobody thought possible, despite the never ending and corrupt Russia Investigation, which takes tremendous time and focus.”

“No Collusion or Obstruction (other than I fight back), so now they do the Unthinkable, and RAID a lawyers office for information! BAD!” Trump tweeted.

Fox News’ Cody Derespina and The Associated Press contributed to this report.