Many schools are struggling to recruit good teachers, Nicky Morgan has acknowledged.
The Education Secretary said she recognised that teacher recruitment is an issue, but warned school leaders that talk of a "crisis" could put people off wanting to join the profession.
Her comments come amid continuing concerns from headteachers and education experts about a growing teacher shortage, especially in some subjects such as physics.
Addressing the Association of School and College Leaders (ASCL) annual conference in Birmingham, Mrs Morgan said: "We know, I know, ministers know, that recruitment is a challenge.
"We hear your concerns. And we know that while the headline data shows a sustained low, national vacancy rate, the reality on the ground for many heads is that they are struggling to attract the brightest and the best."
This year, in a growing economy, leading employers are intending to recruit more graduates than last year from a smaller overall graduate poll, she said.
"Even with all other things being equal, we know that you will be facing a challenge.
"So we are doing all that we can to drive recruitment and improve retention. And we are getting more returners to come back into the profession."
New measures on supporting part-time teachers, particularly women, will be announced on Sunday, Mrs Morgan said, and the results of review groups looking at teacher workload are due to be published in the spring.
"I need your help to tackle this challenge," Mrs Morgan told delegates.
"By all means, lobby me about what more the Government can do to improve recruitment and retention. But let's not inadvertently create a vicious cycle where talk of a crisis actively puts people off entering the profession.
"Let's focus on the commenting to the outside world on what a great profession teaching is, how rewarding it can be and what good teachers have the power to do."
Mrs Morgan also responded to a question on creating a national database of teacher vacancies saying: "We are very interested in that, and I do realise just how much money schools have to spend on vacancies and you have other, better things to be spending money on."