Yahya related to me from Malik, from Nafi, that Abdullah ibn Umar used to say, "Someone in ihram should not be cupped, except when there is no other alternative."
Malik said, "Someone who is in ihram should not be cupped except when it is necessary."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ كَانَ يَقُولُ لاَ يَحْتَجِمُ الْمُحْرِمُ إِلاَّ مِمَّا لاَ بُدَّ لَهُ مِنْهُ . قَالَ مَالِكٌ لاَ يَحْتَجِمُ الْمُحْرِمُ إِلاَّ مِنْ ضَرُورَةٍ .