Here are a few options:
Using diminutives:
* Человечек (chelovechek) - This is a diminutive of "человек" and translates literally to "little person".
* Мужчинка (muzhchinka) - This is a diminutive of "мужчина" and translates literally to "little man".
* Маленький человек (malen'kiy chelovek) - This literally means "small person".
Other options:
* Малыш (malysh) - This means "little one" or "baby" and is a common term of endearment for a small child. It could be used for a little man in some contexts.
* Парнишка (parnishka) - This means "young man" or "lad". It is a less formal and more casual term than "мужчина".
The best choice will depend on the specific context and tone you want to convey.