In the email, Bishop - ranked third in the National Party caucus, after Christopher Luxon and Nicola Willis - likened Hamas' actions in Israel to the Holocaust.
It had been widely shared on social media.
Luxon told RNZ's Morning Report the language used was "strong" and it showed there were high emotions on both sides.
"[The email] is representative of strong emotions on all sides of this debate.
"I acknowledge for our Jewish and Muslim communities it's a difficult time. New Zealand has been consistent in condemning the attacks, in supporting the right of Israel to defend itself, and humanitarian needs [being] a priority.
"It is a tragic tragic set of circumstances that is playing out and that is the way we need to work through it."
National and the outgoing Labour government had both been calling for a humanitarian truce to allow aid into Gaza as the death toll topped 8000 people.
Luxon supported New Zealand's recent vote at the United Nations on the truce - despite being the only Five Eyes partner who voted in favour of the resolution.
Luxon would not confirm whether he would go further and call for a ceasefire.
"We condemn Hamas attacks on Israel [as] barbaric... and unprovoked. We do support Israel's right to defend itself but expect all parties to act in line with international law."
He said that in reality, parties on the ground "don't want a ceasefire at the moment".
"We do believe that starting the Middle East peace process is what's needed in this region, and no military action will secure that."
