Frost, who divorced Law in 2003, was apprehended after an alleged bust-up with former male model James Gooding, who she has been dating for several months.
According to Britain's The Sun newspaper, she was questioned by cops and ordered to report to a London police station.
The publication reports Frost was handed an official police caution on Monday (08Oct12).
A police spokesperson says, "A woman, aged 47, was arrested on suspicion of common assault. The man did not need hospital treatment."
Gooding previously dated Australian pop star Kylie Minogue, but the singer called off their three-year relationship after he allegedly boasted about romancing model Sophie Dahl.