It will be helpful for translators to begin a new paragraph at this point (so Revised Standard Version, Good News Bible).

Now Jonathan sent to Demetrius the king the request that he remove the troops of the citadel from Jerusalem, and the troops in the strongholds: Now is better translated “Meanwhile” (Contemporary English Version). Demetrius~I had agreed to remove his troops from the fort in Jerusalem (1Macc 10.32), but died before doing it. His troops did evacuate all the other fortresses in Judea, except for the one at Bethzur (1Macc 10.12-14). However, there might have been a reoccupation of some of these fortresses, at least at Gezer (1Macc 13.43-48) and Joppa (1Macc 12.33-34). Demetrius~II had granted the Jews several important concessions (verses 32-37), but never agreed to remove the troops from the fort in Jerusalem or from the other outposts in the land.

For they kept fighting against Israel gives the reason for Jonathan’s request to remove these troops. Good News Bible says “since they kept harassing the Jews,” which is probably what was happening. A more helpful model may be “because they kept attacking the Jews.”

In some languages it may be helpful to use direct speech in this verse as follows:

• Meanwhile, Jonathan sent the following message to Demetrius: “Please take your soldiers out of the fortresses in Jerusalem and elsewhere. They keep attacking us.”

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Maccabees. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here.