How to find LED Christmas lights that look more like traditional incandescent bulbs?
Led lamp color is measured in kelvins.  Warm White is 2700 kelvins or 27K.  This is 'supposed' to be equal to incandescent table lamps.  Next is 30k which supposed to be equal to halogen.  Next is cool white which in LED's can range from 39k to 45k.  The next is 50k and then 65k.  The higher the number the bluer the white is.  It sounds like you want 27k.

The bad part of this is on Christmas or string lights, they are made so cheaply that they probably don't put any of this on the packaging.  Another thing about cheaper LED's is even when the color is listed on the package, the color will change from batch to batch.

Click here for Google search on warm white Christmas lights and maybe you can find something more suitable for you.