It is okay to use
git pull http://ahmeditmna:123456@xxxxx.git
I think you mean git clone http://ahmeditmna:123456@xxxxx.git
Technically speaking, yes. http://username:password@domain/path
is a valid URL part of HTTP(S) protocol.
But is that safe or should you do it? No.
Well first, it's better to use HTTPS, if you are pushing / pulling from a public repository it won't be a problem since data is already public, but if it's a private repository your data could be read by an attacker.
But the more important part is anyone having access to the copy of your repository would be able to read your credentials. Just try it (I took the first Python related repository for this example..):
cd /tmp/
git clone 'https://username:password@bitbucket.org/mshibly/python-examples-from-intro-to-python-course.git'
cd python-examples-from-intro-to-python-course/
git remote -v
git remote -v
list repository's remotes URL, let's see:
origin https://username:password@bitbucket.org/mshibly/python-examples-from-intro-to-python-course.git (fetch)
origin https://username:password@bitbucket.org/mshibly/python-examples-from-intro-to-python-course.git (push)
As you can see, your credentials are here, waiting to be read.
And that's even worst if you use this on a server since depending on your general configuration you can find your credentials in logs. Not speaking about the fact you may end by scripting this and have your credentials into a script you may commit and / or store on someone's else server.
The point here is there are not good reasons to do this, but there a plenty of good reasons to not.
No, it's not ok to do this.
I advise you to spend some hours learning how SSH works and configuring your OS.