The Boys in Green boss named a 35 player panel ahead of the Netherlands friendly on May 27, but did not include Hogan in his plans. The 24-year-old qualifies for Ireland through his grandparents, and had been tipped for inclusion after assistant manager Roy Keane watched him at club level, but O'Neill revealed it is not the right time to introduce him to the international setip.
"He has done very well and Roy was pretty impressed with him," O'Neill told reporters.
"We have a number of players at this minute who would be in front of him. He's coming back from injury as well, but definitely, he looks very, very good. I think [a call-up] might have been too early for this one, but he's certainly in mind. I thought about bringing him in, but I just left it at this minute."
Southampton striker Shane Long has been included in the provisional squad, and O'Neill is delighted with how the 29-year-old has been performing for the Saints this season.
"[His form is] really great," the former Sunderland boss admitted.
"He hasn't really looked back since the goal against Germany [last October], that's given him enormous confidence. I can't just put it down to that, but certainly that gave him an enormous boost.
"The second half of the season, particularly the latter part of it, he's just been really excellent and that's great news for us."