Looping inside a if block

The following is common in any programming language.

  foreach(.....)
  {
         if(...)
           ....
  }

I wonder whether it is a good programming practice to use the following. I know it works, but it looks little bit untidy.

  if(....)
  {
        foreach(...)
        {
           ...
        }
 }

Iterating over a collection when some condition evaluates to true is the requirement. But I have never seen this in any kind of sample codes. In a nutshell, I have never noticed such in codes written by other people. But this works and gives me what I want. But I want to avoid writing a loop inside a if block.

Can someone point out an alternative to this ?