Overfull problem with an url

Add option hyphens to package url to allow breaks at explicit hyphens in URLs:

\usepackage[hyphens]{url}

With more breakpoints, it is easier for TeX to break paragraphs into lines without overfull \hboxes.

Using xurl package instead of url (see here):

\documentclass[12pt,twoside]{report}

\usepackage[headheight=18pt,a4paper,width=150mm, top=25mm, bottom=25mm, bindingoffset=6mm]{geometry}

\usepackage[utf8]{inputenc}

\usepackage{fancyhdr}
\pagestyle{fancy}

\setlength\parskip{1em plus 10pt} 
\renewcommand{\headrulewidth}{0.4pt}
\renewcommand{\footrulewidth}{0.4pt}
\usepackage{xurl}

\begin{document}
bla bla bla bla and 
 \url{http://www.msal.gob.ar/chagas/index.php/informacion-para-ciudadanos/el-chagas-en-el-pais-y-america-latina}. Programa Nacional de Chagas del Ministerio de la Nación. 
\end{document}