The incident took place at about 8pm on Monday (July 8) as the girls, aged between 10 and 14, were walking along the footpath behind Finchampstead Baptist Church and California Country Park Woods.
The man is reported to have apologised to the girls before they made their way home.
Police are appealing for information following the incident.
The offender is white man with tanned skin, in his late 20s, between 5ft7ins and 5ft10ins and of slim build. He has short dark hair pushed to one side and light facial stubble. He was wearing a dark blue short sleeved top, black shorts and flip flops.
PC Jonathon Turner-Evans from Lodden Valley Police Station said: "I would like to appeal to anyone who recognises the description given or if they have seen a male fitting this description in the area. This incident has left the four young females very distressed. "
If you can help, please contact PC Turner-Evans via the Thames Valley Police Enquiry Centre on 101.
If you don't want to speak directly to the police you can contact the independent charity Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org.
No personal details are taken, information is not traced or recorded and you will not go to court.