It is narrated from Umm al-Mu'mineen Sayyidah Aisha (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) would kiss while in the state of fasting.
Hadith Referenceالسنن المأثورة / باب صيام من أصبح جنبا / 300
Hadith Takhrijمعانی الآثار للطحاوي : 92/2 اسناده صحيح على شرط الشيخين