The phrase "cautioning against" is correct and usable in written English.
For example, a safety manual might caution against operating heavy machinery without proper training and supervision.
"I understand the voices cautioning against broadening our commitment.
I had been cautioning against such developments all along.
Macron was cautioning against dogmatic answers to practical problems.
The IMF is cautioning against sacrificing productive investment in an obsession with debt targets.
In three new research papers, the fund's economists offered stern admonitions while cautioning against an overreaction.
But Web sites and testimonials cautioning against the practice have proliferated on the Internet.
Some are wary of this trend, cautioning against letting religion too close to government.
Perhaps most problematic: Sen. Rand Paul (R-Ky). is reportedly cautioning against choosing Kavanaugh.
It's a wise ruling that preserves judicial power for extreme cases while cautioning against indiscriminate decrees.
Senator Tom Daschle, soon to be majority leader, is sensibly cautioning against dramatic changes.
He was emphatic in cautioning against misdiagnosing and misapplying computer models without obtaining the necessary proof.
