both.
mercantilism domestically to protect your market from foreign goods.
free trade externally to export your own produced goods to foreign lands, if necessary enforced by big guns.
Er... that's pretty much mercantillism you're describing. The whole idea of that system is to put up tarriffs and other barriers to prevent foreign impots, and using the money to subsidize your own manufactures, industry and export. The desired result is to see lots of production in and export from your nation, while foreign money (gold and silver) flows into your country.
Mercantillism never involves limiting your own exports.
SPOILER: mercantillism actually doesn't work in the long term. There's a reason Britain got rid of it and adopted free trade policies: those were more profitable. With mercantillism, you're keeping out cheaper competitors by artificially keeping prices high, which ultimately damages your economy, and offsets all the perceived benefits of protectionism....
...
however:
Let's talk about a hypothetical situation where there is a government-organised industrial development (leading to possible Industrial Revolution).
If the government itself is organizing the industrial development, it will need a lot of revenue. This can be gained through domestic taxes or through tarriffs, and the latter are the more attractive option. In part because taxing your own economy will drive up prices, and make you less competitive. Combine that with free trade, and foreign rivals will flood your markets with their cheap imports.
So in this particular scenario, you
need to raise tarriffs, and use those to finance your government program of industrialization. In the long term, however, the government will need to cut back on the subsidies and lower the tarriffs, embracing free trade (lest it suffer an economic downturn due to ridiculously high domestic prices and an uncompetitive international position).
So... pretty much what Britain did in the late 18th and early 19th centuries.