(Note: I've rewritten this answer after the OP explained more details of the document's setup.)
To suppress page numbering in a part of the document, one has to both set \pagenumbering{empty} and take care of commands -- such as \tableofcontents, \listoffigures, and \listoftables -- that internally invoke a command (specifically, the \chapter command) which (re)sets the page style of the current page to plain. In the example below, I use the \patchcmd macro of the etoolbox package to "patch" the chapter command. To keep the scope of the modification local to the front matter of the document, I've put a \begingroup ... \endgroup pair around the relevant part of the document. Finally, after the end of the frontmatter, it's necessary to restore plain pagenumbering and to restart the page numbering by issuing the command \pagenumbering{arabic}. Happy TeXing!
\documentclass[12pt,a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[french]{babel}
\usepackage{xcolor}
\definecolor{myblue}{rgb}{0.2,0.4,1}
\usepackage{layout}
\usepackage[margin=2cm]{geometry}
\usepackage{setspace}
\usepackage[pdftex]{graphicx}
\usepackage{array,multirow,pgfplots,filecontents}
\usepackage[justification=centering]{caption}
% Load the 'etoolbox' package to provide to
% patch the '\chapter` command (locally, in this case)
\usepackage{etoolbox}
\begin{document}
\pagestyle{empty} % switch to "empty" page style for front matter of document
\begingroup
% In this TeX group, the first page of new "chapters" should obey
% '\thispagestyle{empty}' rather than the default '\thispagestyle{plain}'.
\patchcmd{\chapter}{plain}{empty}{}{}
\include{title-content}
\color{black}
\doublespacing
\include{dedicaces-content}
\include{remerciement}
\tableofcontents
\listoffigures
\listoftables
\endgroup % end of TeX group
\clearpage
\pagestyle{plain} % revert to "plain" page style
\pagenumbering{arabic} % restart page numbering
\chapter{Introduction générale}
% 19 more "dummy" chapters, just to make the ToC span 2 pages
\chapter{Bla 2}
\chapter{Bla 3}
\chapter{Bla 4}
\chapter{Bla 5}
\chapter{Bla 6}
\chapter{Bla 7}
\chapter{Bla 8}
\chapter{Bla 9}
\chapter{Bla 10}
\chapter{Bla 11}
\chapter{Bla 12}
\chapter{Bla 13}
\chapter{Bla 14}
\chapter{Bla 15}
\chapter{Bla 16}
\chapter{Bla 17}
\chapter{Bla 18}
\chapter{Bla 19}
\chapter{Bla 20}
\end{document}
report?book? something else?) and whether you use any LaTeX packages that may affect the page style and page numbering style that's in effect. You should certainly try (a) issuing the command\pagestyle{empty}immediately after\begin{document}and (b) issuing the commands\pagestyle{plain}and\pagenumbering{arabic}immediately before\chapter{Introduction}. That said, I can't help but remark that it would be a bit unusual not to have any page numbers in the document's front matter area. – Mico Jun 25 '12 at 20:58\thispagesttle{empty}in each of your included .tex files and also have to insert that instruction after the\tableofcontentscommand (and issue a\clearpageafter the front matter). – Mico Jun 25 '12 at 21:36