The inshore lifeboat had attempted to rescue the pair but was unable to get to them, meaning the chopper had to be called in.
The alarm had been raised shortly after 6pm last night when reports came in that the pair were in trouble.
Coastguards were first on the scene and found the girls between Battery Parade and the Spa Pavilion on Whitby's West Cliff beach.
A Coastguard rescue officer equipped in water rescue equipment was able to wade round to the casualties and make contact with them.
The casualties were then helped to a slightly safer location whilst an assessment was made of the quickest and safest way to get them back to safety.
Efforts were made to extract the duo by both boat and by rope, but it was decided that the quickest and safest method was to rescue them by helicopter.
A spokesman for Whitby Coastguard said: "Coastguards quickly established a helicopter landing site on the West Cliff. Coastguards were assisted by officers from North Yorkshire Police in keeping the public at a safe distance from the helicopter operations. With the helicopter having landed, the casualties were checked over by Coastguards and the helicopter winchman paramedic and although cold were thankfully not substantially the worse for their ordeal.
"With school holidays underway and Whitby's tourist season beginning, we hope this will serve as a timely reminder of the importance of familiarising yourself with the tide times."
In any coastal emergency call 999 and ask for the Coastguard.