For Jain monks and nuns, the rule is extremely strict:

• They take the Mahāvrata of absolute ahimsā.
• They are not allowed to intentionally harm any living being, even in self-defense.
• If attacked (by humans, animals, etc.), the ideal response is:

- patience and equanimity, - trying to move away or avoid the situation, - but never to strike back, use weapons, or plan any violent act.

So, for ascetics (sādhus–sādhvīs) your statement is essentially correct: they are expected not to do violence under any circumstance, including self‑defense. Using violence would break their great vows and bind very heavy karma.

A small clarification:

• For lay Jains (householders), limited self-defense or protection of others is tolerated as unavoidable and should be:

- last resort, - with minimum possible harm, - without hatred or revenge, - followed by repentance (pratikraman). ( jainknowledge.com)

But this exception is not given to monks and nuns; their standard is the highest.

You can read a simple explanation on Jain views about necessary or defensive violence here