John Gill Commentary Lamentations 3:52

"They have chased me sore like a bird, they that are mine enemies without cause." — Lamentations 3:52 (ASV)

Mine enemies chased me sore like a bird
That is weak and helpless, fearful and timorous; that flees from place to place when pursued; so it was with the prophet, or rather with the people of the Jews he represents; for here and in the following verses he speaks not only of himself, but of them; who, when they fled out of the city, were chased and pursued by the Chaldeans like a bird, till they were taken; see (Jeremiah 52:7–9) ;

without cause ;
which may be connected with the word "enemies", so the Targum; who were so without cause; they had done them no injury, to make them their enemies; and without reason pursued and chased them in the manner they did.