In traditional doctrines of providence a distinction is made
between ordinary & extraordinary providence (or similar language).
God's ordinary providence is exercised through natural processes. The
scholastic way of speaking is that God as First Cause makes use of
created things as second causes to accomplish his work. This is what I
meant by saying that God acts "mediately".
Extraordinary providence involves miracles. Many writers
insisted (& some still do) that miracles, properly speaking, were events
which were completely beyond the capabilities of nature. IMO that is
very doubtful. But if one holds that view & believes that miracles do
occur, they are providential acts (i.e., things which God does for the
preservation & governance of creation), but they are done by God
in a sense _im_mediately.