... to maintain or regulate order

[WilliamTaft]

Repress and suppress have similar meanings, but there are subtle differences that are worth paying attention to. Both share the general sense of holding back or subduing something, but repress suggests keeping something under control to maintain or regulate order, while suppress suggests a more active curtailment, an active fight against an opposing force.
Source: usage note under repress - American Heritage Dictionary

Is "regulate order" a common collocation?

 

[5jj]

It's certainly not uncommon.

 

[teechar]

I don't think it's all that common.

Google Books Ngram Viewer

Google Ngrams: maintain order, regulate order, keep order, 1800-2022

books.google.com

 

[jutfrank]

I would say it doesn't really come anywhere close to being a collocation. In fact, I don't think it works well at all. You regulate something in order to achieve some kind of order. You can't really regulate order itself, in my opinion.

'Maintain order', on the other hand, works very well and certainly is a common collocation.