Yes, the U.S. and other allies should do everything possible to protect Afghan police. They play a vital role in the fight against the Taliban and other terrorist groups. If they are being specifically targeted, then something needs to be done immediately to protect them further. It seems odd that they are equipped as well as the military.
In order for Afghanistan to become a stable, functioning country on its own, it needs to have a professional, well-trained police force. However, if Afghan police are not adequately protected from serious threats then many quality police officers will quit. This will hurt the country's security in the future. Therefore, the United Sates and NATO need to do more to protect Afghan police to promote a stable security force.
When the war in Afghanistan is all under the 'War on Terror', I think it is only right that the U.S. and other allies protect the Afghan police from the Taliban. The Taliban are a terrorist organization, and the Afghan police need help fighting against them. The U.S., it's allies, and the Afghan police all have the same goals - to fight terrorism and restore peace in the region.
Though Taliban targets Afghan police the U.S. and other allies should abide by the new US rules of engagement in Afghanistan. Despite several years of US and other allies supporting Afghanistan against the Taliban, nothing much seems to have changed. In the first instance the Afghan forces are afraid that the Helmand province would be captured by Taliban since this province has a lucrative heroin trade. Most of the Afghan population is suffering because of the heroin trade, so whether the Afghan forces or the Taliban takes hold of the Helmand province the common people would still suffer. The biggest fear of the Helmand province being captured by the Taliban is of course the spread of Taliban and growing threat of Islamist terror attacks worldwide.