Trump is known to be a big Brexit fan – being chums with former UKIP leader Nigel Farage and openly endorsing Britain's exit from the EU.
The Prime Minister has previously revealed that Mr Trump told her to "sue the EU" and "not go into negotiations".
May now sees Brexit slipping through her fingers as MPs voted to take no deal off the table last night, potentially delaying Britain's exit from the EU.
MPs are now set to overide May again tonight as they work to secure an extension to Article 50, meaning Britain won't leave on the original legally binding date of March 29.
The US President was meeting with Irish premier Leo Varadkar when he let rip with his thoughts on Brexit, saying May should have followed his advice.
“It's tearing a country apart”
Trump said that Brexit is "tearing countries apart" and claimed the EU has been "very tough to deal with".
He also backed calls for the Brexit deadline to be extended, saying "they are probably going to have to do something".
Brexiteers fear the wheels are now in motion totally cancel Britain's leaving of the EU, with pressure mounting for a so-called People's Vote.
May could see a lifeline thrown to her by rebel Tory MPs however, with rumours Jacob Rees Mogg's faction is ready to finally back her twice-defeated and bitterly unpopular deal on the condition she quits as PM.
The US President's comments came after TV star Piers Morgan urged him to swoop in, saying: "Only one person can now sort out this ridiculous Brexit mess: Donald Trump.
"He'd take no sh*t from the EU, or Parliament, or anyone. And he definitely wouldn't lose his voice. Mr President, my country needs YOU."
US PRESIDENT: Donald Trump accused Theresa May of not taking his advice (Pic: GETTY)
Trump said: "It's a very complex thing right now, it's tearing a country apart, it's actually tearing a lot of countries apart and it's a shame it has to be that way but I think we will stay right in our lane."
"I'm surprised at how badly it has all gone from a stand point of negotiations but I gave the Prime Minister (Theresa May) my ideas of how to negotiate it.
"She didn't listen to that and that's fine but it could have been negotiated in a different manner."
"I hate to see everything being ripped apart now."
He added: "The EU has been very tough to deal with and frankly it's been very one-sided for many years so we are changing that around."
BREXIT: Donald Trump was asked about Brexit while meeting with Leo Varadkar (Pic: GETTY) Related Articles
'GOING BADLY': Donald Trump said he expected Britain to stay in the EU beyond March 29 (Pic: GETTY)
Asked if he thinks the Brexit deadline should be extended, Mr Trump said: "I think they are probably going to have to do something because right now they are in the midst of a very short period of time, at the end of the month and they are not going to be able to do that.
"We can do a very big trade deal with the UK. we are also re-negotiating our trade deal with the Read More