Try this (assuming you're working with master branch and your remote is called origin):
git push origin HEAD^:master
HEAD^ points to the commit before the last one in the current branch (the last commit can be referred as HEAD) so this command pushes this commit (with all previous commits) to remote origin/master branch.
In case you're interested you can find more information about specifying revisions in this man page.
Update: I doubt that's the case, but anyway, you should be careful with that command if your last commit is merge. With merge commit in the HEADHEAD^ refers to the first parent of that commit, HEAD^2 - to its second parent, etc.