Juncker told MEPs in Strasbourg on Wednesday that he "cannot accept Europe as the continent of youth unemployment."
But the European Youth Forum, a platform of youth organisations in Europe, said Juncker's "good words are at odds" with the subsequent announcement of an effective cut in funding of more than three-quarters in the EU's Youth Guarantee as compared to 2014-2016 funding.
Reacting to Juncker's speech, it said, "Without the political will and funding to effectively implement the Youth Guarantee, youth unemployment will continue in Europe.
"Similarly, more details are needed on the newly announced European Solidarity Corps which must support, not replace or just rehash the good work already being carried out by young people and youth organisations."
The statement went on, "It is extremely disappointing that at very difficult times for Europe, and especially its young people, the Commission's answer does not match the promise of Juncker's speech, by implementing an effective cut in Youth Employment Initiative funding."
It claims this will be slashed from €6bn over 2014-2016 to €2bn for the next four years.
The Forum is now calling on the European Parliament and Council to ensure there is "at least" the same amount of funding for the Youth Employment Initiative for the 2017-2020 period.
Its President Johanna Nyman said, "Europe is on a cliff edge: decisions made now impact all of our futures, but especially young people's.
"While we welcome Juncker's concern for youth, we are past the time for nice words, which is what he offered us in his speech. What we need is answers, detail and real, new investment in young people. If he wants to empower citizens, Juncker must include us and create a real dialogue with young people about our future.
"We call on member states and the parliament to continue existing levels of funding for the Youth Guarantee."
The future funding of the EU will be one of the issues discussed at an informal EU summit in Bratislava on Friday.
Nyman added, "European leaders must now, at the summit in Bratislava, show their commitment to youth and invest in us in order to release the huge potential that we have. We look forward to hearing what importance they place on all of our futures."
Meanwhile, the European University Association (EUA) said it "deplores" that research, innovation and higher education "hardly featured" in Juncker's speech.
In his address to Parliament, Juncker set out a plan to strengthen investment to support jobs and growth, specifically through an extension and amplification of the European Fund for Strategic Investments (EFSI).
But the EUA said, "Given the strong evidence that research, innovation and higher education are vital areas for investment in order to create jobs and growth in Europe, we believe that they should be given higher priority."