How to match lines with a rule

I want to search for all lines that:

• start with a numeric repeat (one or several times) which is not followed by dot and a whitespace character

Given Lines

1. TEST 1 : DataLogFile
11. TEST 2 : Inter Citro File
111. TEST 3 : Inter Citro File
111.TEST4 : Match this

Expected Result

Matched only last line

111.TEST4 : Match this

Regex

I try with regex ^[0-9]+(?!. ).* to match normaly only the last row because there is no whitespace character after the dot.

Tested in Regex101

Actual Result

Matched 3 last lines

11. TEST 2 : Inter Citro File
111. TEST 3 : Inter Citro File
111.TEST4 : Match this

[EDIT]

When I try the SaSkY response, it will only match lines that have digits after dots after no blank characters.

I try to delete dot after digits it will not match.

Demo

Expected Result :

111.TEST4 : Match this
111TEST4 : Match this

>Solution :

Try this:

^\d+(?:\.\S|[A-Z]).*

• ^ start of the line.
• \d+ one or more digits.
• \. literal dot .
• \S any character except a whitespace character.
• .* zero or more characters.

See regex demo