The world-renowned cellist said some youngsters were denied access to music and insisted that pupils that played instruments performed better with their school work.
Mr Lloyd Webber was at Telford Langley School yesterday to watch hundreds of pupils perform a concert as part of the In Harmony programme that he founded.
From modern classics to beautiful music of the past, more than 450 primary school pupils came together to play violins, percussion instruments and keyboards at a concert watched by the , cellist and conductor.
There were tears from parents in the audience as 380 children as young as five and six played the likes of Ode to Joy, Adele's Hello, Queen's We Will Rock You and the William Tell Overture. Another 78 sang in choirs.
The concert, which was held in the Telford Langley School sports hall, featured pupils from Old Park Primary playing violins and other classical instruments in smaller, separate orchestras and as a whole across an hour-long performance.
The In Harmony project aims to transform the lives of children in deprived communities through ensemble music making.
Mr Lloyd Webber said: "Telford got on board with the In Harmony project in 2012, and it's been a wonderful thing to see.
"The goal of In Harmony is to bring people together by playing instruments. Music can save children from lives of poverty and crime."
The musician used the opportunity to attack the lack of emphasis on music and the arts in education.
He said: "I'm so depressed to see the government's attitudes to music in the school curriculum.
"It's completely unfair that some people get to play music and others do none at all. It's been proven by people who study this that children who play an instrument do better in the rest of their school work – it's been proven all over the world.
"So why the government should decide to take all arts out of the school curriculum is a complete mystery, and I think that society will pay for that in the future.
"We have to keep up the pressure. We have to make noise about music, because it's worth making noise about.
"I'm incredibly proud to have been here."
Mandie Haywood, headteacher at Old Park Primary said: "It was awesome. It made the hair stand up on the back of my neck.
"To watch that number of children all playing and sounding amazing – I am immensely proud of the way our children have responded to this programme and of all the staff who've worked with them. It's been tremendous.
"What's been fantastic about this project is it's been so embraced by the staff and the children but everybody will do whatever it takes to get everything organised.
"We needed a big venue and this is the only venue we found that could have this amount of children together. Once we said this is where we were coming, everybody worked out the details and just got on with it really.
"We had one rehearsal with all the orchestras together at 1pm on the day of the concert, but it came together really nicely.
"Staff are so supportive and we have people from In Harmony as well – we are just one big team."
Steve Carter, head of school at Telford Langley, said: "It was absolutely amazing. Right at the start of the event I thought it was a whole range of schools, but I soon realised that it was only Old Park. That is quite an achievement.
"Music is like anything, the earlier you start the better you're going to be.
"It's on us now to make sure that we nurture the talent and enthusiasm of pupils who join us so that they can become spectacular musicians.
"There must be a full range of opportunities. Maths, science and English are important, but if schools move away from creative arts that would be a really sad thing. We want a balanced curriculum so pupils can develop any skills they might have, whether it's music or whether it's sport."