The minister said the recession had led to a squeeze on public spending
The education secretary has admitted he does not expect teacher numbers to return to the level the SNP government inherited from the last administration.
Mr Russell's predecessor Fiona Hyslop pledged three years ago that teacher numbers would remain at 53,000, but since then they have fallen by 2,000.
Mike Russell said it had not been possible for local authorities to employ the same number of teachers.
Opposition parties have described the admission as astonishing.
The decline has lead to accusations of broken promises.
But Mr Russell said the recession had led to a squeeze on public spending.
Speaking to the Times Educational Supplement Scotland, he said: "I hope we will be able to sustain the number of teachers.
"There has been a reduction that I don't see us making up again, to be honest.
"Equally I don't want to see a further substantial cut."
Labour's education spokesman Des McNulty said: "After losing over 2,000 teachers Mike Russell is not ruling out even further reductions in teacher numbers.
"This is an astonishing admission from the minister.
"What is clear is that the SNP are losing control over the education system.
"Teacher numbers are in freefall, Curriculum for Excellence is in turmoil, the PE pledge is going nowhere, colleges are being forced to turn away students and yet the minister is still banging on about smaller classes that he knows he can't deliver."
Liberal Democrat education spokesperson, Margaret Smith, said: "The education secretary has admitted defeat.
"This government won't get teacher numbers back up again.
"But given they are cutting hundreds of teacher training places this year and the next, this isn't a surprising admission.
"The plummeting number of teachers under the SNP will have a serious impact on the quality of education that can be delivered in our classrooms and could jeopardise the future of teacher training facilities across the country."