Short answer. No. It is a prohibited practice to influence or attempt to influence any person or entity not to employ a worker who has not applied through the agency. The pressure itself is unlawful, whether or not the employer gives in and whether or not you learn of it.
What the law says
To influence or to attempt to influence any person or entity not to employ any worker who has not applied for employment through his agency
Labor Code, Article 34 — Prohibited Recruitment Practices. Read the full provision →
The clause bans the pressure, not just its success
The prohibited act is to influence or to attempt to influence any person or entity not to employ any worker who has not applied for employment through his agency. As with several items on this list, the attempt is enough. An agency that tells a client it will withdraw its services if the client hires directly has done the prohibited thing at the moment it says so; whether the client complies goes to the harm, not to the breach. That matters for workers, because the conversation almost always happens somewhere you cannot see it and its effect on you is silent.
What the rule protects is the direct route to a job
The provision assumes something worth stating plainly: a worker is entitled to be hired without passing through anybody's agency. Placement services exist to open access to employment, and an agency that makes itself a toll gate has inverted its function. Read alongside the neighbouring ban on charging more than the prescribed fees, the pattern is clear enough — the Code is hostile to arrangements that force a fee into a hiring that did not need one.
How this looks from the worker's side
You rarely see the prohibited act; you see its shadow. An employer who was interested becomes unresponsive after learning you approached it directly. You are told the post can only be filled through a named agency. A former applicant is warned that agencies talk to one another. None of that proves the clause was broken, and it is important to be honest about the difference between an inference and evidence. But it is the shape the breach takes, and it is a reason to write things down at the time rather than afterwards.
What would actually make the case
Something in writing from the employer's side is usually what turns suspicion into a complaint: an email saying applications are only accepted through a particular agency, a message relaying what the agency said, a job posting that names the requirement. Note dates, the person who told you, and what exactly was said. If several applicants experienced the same thing at the same employer, that pattern is worth assembling in one place. Take it to a lawyer before confronting the agency, because a confrontation tends to dry up the evidence.