The bill, which was approved by the US Senate late Wednesday, was expected to keep the government funded and open for business through February 8, 2019.
"We just had a very long, productive meeting with the president," Ryan told reporters. "The president informed us that he will not sign the bill that came from the Senate last evening because of his legitimate concerns for border security."
"We want to keep the government open, but we also want to see an agreement that protects the border. We have a very serious concern about securing our border," he added, stressing that lawmakers would simply have to go back to the drawing board.
"The president said he will not sign this bill, so we're going to go back and work on adding border security to this."
In a subsequent statement, White House Press Secretary Sarah Huckabee Sanders wrote, "We urgently need funding for border security, and that includes a wall."
The rejected spending bill did not provide for Trump's specific border wall vision, instead offering $1.3 billion for border security and fencing, according to WTOP. Trump's requested $5 billion was nowhere to be seen.
US House Majority Whip Steve Scalise (R-LA) did give reporters insight on the next steps for lawmakers, suggesting that new language would be added in regards to border wall funds. However, it's unclear if the new stop-gap spending bill will be able to actually pass through the House and Senate.
"Boy, we can't have government shutdown. It's never good," Sen. Susan Collins (R-ME) told CNN after being informed of Ryan's announcement. "How many times do we have to learn that?"
Addressing the matter at the signing of the 2018 Farm Bill, Trump stood firm to his guns, saying "At this moment there is a debate over funding border security and the wall… I've made my position very clear — any measure that funds the government must include border security — has to. Not for political purposes but for our country, safety, for community."
Citing the US massive expenditures on foreign wars, the president said "I am asking Congress to defend the border of our nation for a tiny fraction — a tiny fraction — of [their] cost."
"Walls works, whether we like it or not, they work better than anything," Trump later added.
Lawmakers have until midnight Friday to stave off a partial government shutdown.