All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
There is no harm in this, as in principle it is permissible to kiss the children as a sign of love, affection and mercy. Kissing the children is something confirmed by the Sunnah of the Prophet and some scholars stated that this is recommended. The evidence proving it being recommended is that Abu Hurayrah narrated that Al-Aqra' Ibn Haabis saw the Prophet kissing Al-Hasan and said: "I have ten children and I never kissed one of them.” Thereupon the Prophet said: "Whoever is not merciful will not be treated mercifully." [Muslim]
Allaah Knows best.