Jake shouldn't look into Neytiri's ikrans eyes as that ikran is Neytiri's and no one elses. Remember Jake could look into his own ikrans eyes but no one else could. So it makes sense that he can't look into other ikrans eyes. He is specially bonded to his own, but not to others, so he cannot look into their eyes. It is plausible that prolonged eye contact with an Ikran or Banshee will goad it into attacking anyone except the one it bonded with.